Ohm's Law Viva Questions and Answers
December 31, 2019

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Ohm's Law Experiment Viva Questions and Answers
(i) State Ohm's law
Ans: At constant temperature the ratio of the potential
difference between the end of a conductor to the current through it is
constant. V/I = constant
(ii) Distinguish between emf and potential difference
Ans: emf is the potential difference between the terminals
of a cell when no current is drawn from it. It is equal to the amount of work
done by the source in moving unit charge once around a complete circuit.
Potential differences between two points on a conductor are
the work done in moving unit charge from one point to other.
(iii) What is meant by specific resistance or resistivity?
Ans: ρ = RA/ l. It is equal to the resistance of a wire
of length one metre and cross sectional area 1 m^{2}
(iv) What is the unit of resistivity?
Ans: Ohmmeter. Ωm
(v) Why are connecting wires thick and covered with
cotton thread?
Ans: Thick copper wire has negligible resistance. They are
covered with cotton to avoid short circuiting.
(vi) What is the material of wire used for making a
rheostat?
Ans: Manganin or constantan
(vii) What is the effect of temperature on resistance?
Ans: Resistance of a wire increases with temperature
(viii) How will you convert a galvanometer into (a)
ammeter (b) voltmeter?
Ans:
(a) By connecting a low resistance in parallel.
(b) By connecting a high resistance in series
(ix) Is Ohm's law a universal law?
Ans: No. It is not a universal law. It fails on semi
conductor and for resistances at very low temperature
(x) What is super conductivity?
Ans: In some substances the resistance completely disappears
below a critical temperature. This phenomenon is called super conductivity
(xi) What happens if voltmeter is connected in series in
a circuit?
Ans: A voltmeter is an tool for finding the potential
difference between two points. Hence the voltmeter is connected between the two
points. More over the voltmeter has a very high resistance. Hence the current
in the circuit is very much reduced.
(xii) Aim of the Ohm's Law Experiment?
Ans: To study current—voltage relationship (i.e. to verify
Ohm's Law) using an ammeter and a voltmeter; and, hence to find the resistivity
of the given resistor.
(xiii) Apparatus of the Ohm's Law Experiment?
Ans: Lead accumulator, a resistance wire (resistor),
ammeter, voltmeter, rheostat, key etc.
(xiv) Theory of the Ohm's Law Experiment?
Ans: If V is the potential difference applied to a conductor
of resistance R and I is the current flowing through the conductor, according
to Ohm's law,
V/I = R, a constant
If r is the radius
and l is the length of the conductor, the resistivity of the conductor,
ρ = R x (π r^{2})/l
(xv) Procedure of the Ohm's Law Experiment?
Ans: The accumulator, resistance wire R, ammeter, rheostat
and key are connected in series. The voltmeter is connected in parallel to R.
The circuit is closed and the rheostat is adjusted to make
voltmeter to show a definite reading V. The reading I of the ammeter is
noted. V/I is calculated.
Adjusting the rheostat suitably, a number of sets of values
are noted for V and I. In each case V/I is calculated. It is found to be a
constant verifying Ohm's law.
A graph is drawn with V along the Yaxis and I along the
Xaxis. The graph is a straight line. This also verifies Ohm's law.
The mean value of V/I is calculated. This gives the
resistance R of the resistor. R is also calculated from the graph by finding
its slope. The average value of R is found out. The radius r of the resistor is
determined using a screw gauge. Its length l is also measured. The
resistivity ρ
of the resistor is calculated from the equation,
ρ = R x π r^{2}/l
ρ = R x π r^{2}/l
Jolly's Bulb Apparatus Experiment
December 28, 2019

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The Jolly's Bulb Apparatus Experiment Viva Questions
(i) State the unit of pressure in S.I.
Ans: Nm^{2}
(ii) What is one atmosphere?
Ans: It is the pressure exerted by a column of 76 cm of
mercury at 0 °C.
P = hdg = 0.76 x 13.6 x 10^{3} x 9.8 = 1.013 x 10^{5}
Nm^{2}
(iii) Why should the air enclosed in the bulb be dry?
Ans: The presence of water vapour alters the reading
(iv) State Charles law
Ans: The volume of a given mass of gas varies directly as
its temperature in Kelvin scale when pressure is kept constant. The pressure of
a given mass of gas varies directly as its temperature when volume is kept
constant ie, V ∝ T and P ∝ T
(v) Why do you use a capillary tube to connect the bulb to
the reservoir?
Ans: To ensure that most of the air enclosed is at the
constant temperature of the bath
(vi) What is the boiling point of pure water at normal
pressure in Kelvin scale?
Ans: 273 K
(vii) How do you define pressure coefficient of a gas?
Ans: It is defined as the ratio of the increase in pressure
of the gas at constant volume per degree rise of temperature to its pressure at
0 °C
(viii) Is the pressure coefficient the same for all gases?
If so what is its value?
Ans: Its value is same for all gases and is equal to 1/273
(ix) Aim of the Jolly's Bulb Apparatus Experiment?
Ans: To study the relation between pressure and temperature
of a sample of air at constant volume
(x) Apparatus of the Jolly's Bulb Apparatus Experiment?
Ans: Jolly's bulb apparatus, water bath, thermometer, etc.
The Jolly's bulb apparatus consists of a spherical glass bulb A connected to a
narrow capillary tube bent twice at right angles. There is a fixed mark M made
on this tube as shown in the figure. The free end of the tube is connected to a
reservoir R of mercury by means of thick rubber tubing. The reservoir can be
raised or lowered and can be fixed in any position. The readings of the mercury
levels may be noted on a scale S.
(xi) Theory of the Jolly's Bulb Apparatus Experiment?
Ans: For a given mass of gas (air) at constant volume, the
pressure P is directly proportional to its absolute temperature T.
i.e., P ∝ T or (P/ T) = a constant
Boyles Law Viva Questions
December 26, 2019

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Boyles Law Viva Questions and Answers
(i) What is the S.I. unit of pressure?
Ans: N.m^{2}
(ii) Atmospheric pressure at sea level is 0.76 m of mercury.
What is the pressure in N.m^{2}? Density of mercury = 13.6 x 10^{5}
kg/m^{3}.
Ans: P = hdg = 0.76 x 13.6 x 10^{5} x 9.8 = 1.013 x
10^{5}Nm^{2} or one Atmosphere.
(iii) State Boyles law
Ans: At constant temperature, the volume of a given mass of
gas varies inversely as its pressure ie, v ∝ 1/p or, pv = constant
(iv) What is gas constant? It is a universal constant for
all gases at S.T.P.
Ans: R =PV/T = 1.01 x 10^{5} x 22.4 x 10^{3}/273
= 8.3 J/mol/k.
(v) What are the limitations of Boyles law?
Ans: It does not hold good for high pressures and low
temperatures. It is also not true for saturated vapour.
(vi) What is critical temperature?
Ans: It is the temperature above which a gas cannot be
liquefied by applying pressure.
(vii) Do all gases obey Boyles law
Ans: Real gases do not obey Boyles law. So called permanent
gases like O_{2}, H_{2}, etc obey Bolyle's law at ordinary
temperature and pressure.
(viii) What is an ideal gas?
Ans: A gas which obeys Boyles law and Charles law is called
perfect gas or ideal gas. Intermolecular force is zero
(ix) Why do we use mercury for measuring pressure
Ans: It and does not wet glass. Hence a small column of
liquid is enough
(x) What is the shape of P.V. diagram?
Ans: It is a part of a hyperbola.
(xi) Aim of Boyles Law Experiment?
Ans: To study the variation of volume of a sample of air
with its pressure at constant temperature using Boyle's law apparatus.
(xii) Apparatus of Boyles Law Experiment?
Ans: Boyle's law apparatus Boyle's law apparatus consists of
a uniform glass tube AB closed at one end. It is fixed vertically on a stand
with its open end downwards. The tube is connected to a reservoir R by means of
a rubber tube. The reservoir contains mercury. The glass tube AB contains pure
dry air. The reservoir can be raised or lowered and can be fixed at any
position. Thus the pressure and volume of air inside the glass tube can be
varied. A scale is fixed between AB and the reservoir.
(xiii) Theory of Boyles Law Experiment?
Ans: According to Boyle's law, at constant temperature,
volume V of a given mass of gas (air) is inversely proportional to its pressure
P.
i.e., P ∝ 1/V
Therefore, PV = a constant.
Since the glass tube is uniform, V ∝ l,
the length of the air column in the glass tube.
P ∝ (1/l); ie, Pl = a
constant
Inclined Plane Viva Questions with Answers
December 24, 2019

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Inclined Plane Viva Questions with Answers
(i) What do you
understand by an inclined plane?
Ans: It is a smooth plane hinged to the base, so that it can
be set at any desired angle.
(ii) Why do you oil the pulley and the axle of the
roller?
Ans: To eliminate friction
(iii) The roller of weight W is in equilibrium on a
smooth inclined plane of angle θ, and the effort ‘P' is required to
keep the roller in equilibrium. How are they related
Ans: P = W sinθ
(iv) What is the shape of the graph and between P and sin
θ?
Ans: The graph is a straight line.
(v) What is the significance of the slope of the graph?
Ans: The slope of the graph gives the weight of the roller
(vi) What is the mechanical advantage of the inclined
plane?
Ans: It is the ratio of the weight of the roller to the
effort. M.A = W/p
(vii) Theory of Inclined Plane Experiment?
If P is the force
(effort) applied parallel to an inclined plane upwards on a roller of mass m
just to keep roller in equilibrium, then,
P = mg sin θ; where mg sin 0 is the component of
the gravitational force (ie., the component of the weight W of the roller)
acting downwards along the inclined plane. P ∝ sin θ; where sin θ
=h/l;l is the length and h the height of the plane.
(viii) Procedure of Inclined Plane Experiment?
The weight w of the scale pan is found out by a common
balance The plane is adjusted to a convenient angle θ. The roller is placed on the
plane and the pulley adjusted to make the string parallel to plane. Weight w_{1}
is placed in the pan to make the roller just move up the plane with a uniform
speed. Next, keeping the roller near the top edge of the plane, the weight w_{2}
required in the scale pan to make the roller just to move down with uniform
speed is found out. The mean effort,
P= [(w_{1} + w_{2})/2] + w
The downward force along the inclined plane acting on the
roller on account of the gravitational force, i.e., mg sin θ,
is equal to the effort P.
P = mg sin θ;
where m = W, is the mass of the roller.
To find sin θ, the length l and the height h
of the plane are measured. Then, sin θ is calculated from the equation.
sin θ = (h/l)
The experiment is repeated for different angles of the
plane. A graph is drawn with P along the Yaxis and sin θ along the Xaxis. The graph
is found to be straight line. This shows that P which is equal to the component
of the weight of the roller along the plane is directly proportional to the
sine of the angle of the inclined plane. The slope of the graph gives the
weight of the roller.
The angle θ of the plane is noted from the value
of sin θ
(Use scientific calculator or logarithm table). A graph is drawn with P and θ.
The graph is a curve bent downward. This gives the relation between the components
of the weight of the roller along the plane at the angle of the plane.
Resonance Column Viva Questions
December 23, 2019

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Resonance Column Viva Questions and Answers
Ans: When two waves of the same frequency and amplitudes travel in opposite directions along a straight line at the same speed, their super position gives rise to stationary waves
(ii) What are nodes and antinodes?
Ans: Node is a position of zero displacement and antinode is a position of maximum displacement
(iii) In a stationary wave what is the distance between successive nodes?
Ans: λ/2, where λ is the wave length.
(iv) What is end correction or edge effect?
Ans: The antinode at the open end of a tube is formed slightly out side the open end. The distance from the open end to the antinode is called end correction e = 0.3d where d is the diameter of the pipe
(v) What is meant by resonance?
Ans: When two notes of the same frequency are sounded together the intensity of sound is maximum and they are said to be in resonance or in unison
(vi) The experiment is called resonance column experiment why?
Ans: When we excite a tuning fork and hold it at the mouth of the tube at resonance the frequency of the air column and the frequency of the turning fork are equal. We obtain the frequency of the air column by resonance method
(vii) What is the effect of temperature on the velocity of sound in air?
Ans: The velocity of sound in air is directly proportional to the square root of temperature in Kelvin scale v ∝ √T.
(viii) In a resonance column experiment what is the functions of water in the jar?
Ans: It only acts as an agent for closing the tube to make the tube a closed tube of easily variable length
(ix) What is meant by supersonic speed?
Ans. The speed greater than that of sound in air ie, 331 m/s at 0°C
(x) If we take kerosene oil in place of water in the resonance column experiment will the resonance position change?
Ans: Remains unchanged
(xi) Why is second resonance feebler than the first?
Ans: At second resonance the vibration in the air column corresponds to the first overtone which is very week
(xii) What type a waves you get in resonance column?
Ans: Longitudinal
(xiii) Is it necessary to have a tube of circular cross section?
Ans: Not necessary.
(xiv) Aim of Resonance Column experiment?
Ans: (a) To determine the velocity of sound in air at room temperature by the resonance column and hence to determine the velocity of sound in air at 0°C.
(b) To find the end correction.
(xv) Apparatus for the Resonance Column experiment?
Ans: Resonance column apparatus, tuning forks, rubber hammer etc. Resonance column apparatus includes a long metal tube erected vertically in a tall jar containing water. The tube can be set in any desired position. The length of the air column in the tube can be varied by stretching or lessening the tube.
Sonometer Viva Questions and Answers
December 21, 2019

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Sonometer Practical Viva Questions and Answers
Ans: No, A material medium is needed for its propagation
(ii) What are the frequency limits of audibility?
Ans: 20 Hz and 20,000 Hz
(iii) What type of waves are light waves and sound waves?
Ans: (a) Transverse (b) Longitudinal
(iv) On what factors does the frequency of a tuning fork
depend?
Ans: It depends on the nature of the material and length of
the prong
(v) What type of waves are produced in a sonometer wire?
Arts: In the tuned position stationary waves are produced.
Otherwise there are transverse waves
(vi) Why is the wooden box of the sonometer hollow?
Arts: Air in the box vibrates in resonance and increases the
intensity of sound.
(vii) What are the functions of the bridges?
Ans: They reflect the sound and produce stationary waves
(viii) Can a rubber cord be used in place of the wire?
Ans: The rubber cord is not rigid and so its vibration die
down quickly.
(ix) What are beats?
Ans: When two notes of nearly equal frequencies are sounded
together there is waxing and waning of sound ie, ups and downs in intensity.
This phenomenon is called beats
(x) What happen when the paper rider in the sonometer
experiment flies off'?
Ans: It happens when the frequency of the wire between the
bridges and the tuning fork are exactly equal
(xi) What happen to the frequency of the turning fork
when one of the prongs is loaded with wax?
Ans: The frequency of the fork decreases
(xii) What are the factors on which frequency of the
segment of a string depends?
Ans: n ∝ 1/l ; n ∝ 1/√T and n ∝ 1/√m
(xii) Aim of Sonometer experiment?
To find the relation between frequency and length, for a
constant tension, frequency and diameter of a stretched string.
(xii) Apparatus for the Sonometer experiment?
Sonometer, slotted weights, tuning forks of known
frequencies, rubber hammer, paper rider, steel wire, etc. The sonometer
consists of a long hollow wooden box with a peg at one end and a vertical
pulley at the other end. One end of the experimental wire is attached to the
peg and the other passes over the pulley. To keep the wire under tension, a
suitable weight is suspended at the free end of the string by a weight hanger.
Two movable bridges A and B are provided for the purpose of altering the vibrating
length of the wire.
(xiii) Theory of Sonometer experiment?
The frequency n of transverse vibration of a string stretched
under a constant tension T is inversely proportional to the length l of the
string.
i.e., n ∝ (1/l);
Therefore, n x l = a constant
(xiv) Procedure of Sonometer experiment?
The bridges A and B are placed at a small distance apart. A
light paper rider is placed on the string between the bridges. A tuning fork of
frequency n is excited and its stem is pressed on the sonometer box between the
bridges. The length of the string is altered by adjusting the distance between
the bridges till the rider vibrates vigorously. This happens when the segment
AB of the string vibrates in unison with the tuning fork. The length l of the
vibrating segment is measured and n x l is calculated.
The experiment is repeated with the other tuning forks
without changing the tension. In all cases it is found that nl is a constant.
A graph is plotted with n along the Xaxis and (1/l) along
the Yaxis. The graph is found to be straight line. This also shows that n ∝
(1/l).
Surface Tension and Viscosity Viva Questions
December 17, 2019

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Surface Tension and
Viscosity Experiment
The surface tension (capillary
rise) Viva Questions and Answers
(i) Define surface
tension
Ans: It is defined as the force acting tangential to the
liquid surface and perpendicular to unit length of an imaginary line drawn on
the surface of the liquid
(ii) What is the unit
and dimension of S.T?
Ans: UnitNm^{1}; Dimension MLT^{1}
(iii) How is surface
tension related to surface energy?
Ans: They are the same.
(iv) What is the
difference between adhesive and cohesive forces?
Ans: Attraction between molecules of the same kindcohesive.
Attraction between molecules of different kindadhesive.
(v) What is angle of
contact?
Ans: The angle between the tangent to the liquid surface at
the point of contact and the solid inside the liquid.
(vi) What is meant by
capillarity?
Ans: Rise of liquid in capillary tube is called capillarity
(vii) For mercury
there is capillary depression. Why?
Ans: Angle of contact is oblige (140 °)
(viii) What are the factors
on which capillary ascent depends?
Ans: Inversely proportion to the radius, inversely proportional
to density and directly proportional to surface tension.
(ix) If the angle of contact were 90°. What is
capillary accent?
Ans: Zero
(x) Is surface tension
is a molecular phenomenon or atomic
Ans: Molecular phenomena.
(xi) Aim of surface
tension experiment?
Ans: To find the surface tension of water by capillary rise.
(xii) Apparatus for
the Surface tension experiment?
Ans: A narrow capillary tube of uniform bore of known
radius, beaker containing water, travelling microscope and so on.
The Viscosity Viva
Questions and Answers
(i) Define the
coefficient of viscosity.
(ii) What is Stoke's
formula?
(iii) What is meant by
Reynold's number?
(iv) Give the Newton's
equation for viscous force.
(v) Define the unit
'poise'
Ans: It is the unit of viscosity in C.G.S system. The unit
is in honor of Poiseuille who did important works on viscosity
1 poise = dynes. second/cm^{2}
(vi) What is meant by
terminal velocity?
(vii) What is the
effect of temperature on viscosity of liquids?
Ans: Viscosity decrease with the increase in temperature.
(viii) What is the
effect of temperature on the viscosity of gases?
Ans: The viscosity of gasses increase with rise in
temperature.
(ix) Aim of the
viscosity experiment?
Ans: To determine the coefficient of viscosity of a given
liquid by measuring the terminal velocity of a given spherical body.
(x) Apparatus for the
viscosity experiment in lab?
Ans: A tall glass jar of about 1 m long and 2 cm radius,
viscous liquid (ex: castor oil or diesel), lead shots or small ball bearings of
different size, screw gauge, stop watch etc.
Simple Pendulum Viva Questions and Answers
December 12, 2019

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Simple Pendulum Viva
Questions and Answers
(i) Who invented
simple pendulum?
Ans: Galileo
(ii) Is `g' a vector
quantity?
Ans: yes
(iii) What is the
effective length of a simple pendulum?
Ans: It is the total length from the point of suspension to
the centre of gravity of the bob
(iv) Why do we use
heavy bob which is small in size?
Ans: A heavy bob has enough restoring force to overcome the
air resistances. A small bob has less resistance due to air. So heavy bob,
small in sizes is used as bob
(v) What is a seconds
pendulum?
Ans: It is a simple pendulum whose time period is 2 seconds.
It takes one second to move from one extreme position to the other end.
(vi) If the given bob
is replaced by a wooden bob of the same size will the time period change?
Ans: It remains the same
(vii) What will happen
to the time period if a simple pendulum is setup on the surface of the moon?
Ans: The time period will increase as the value of 'g' on
the surface of the moon in less than that on the surface of the earth.
(viii) While
oscillating, the amplitude of the pendulum must be smallwhy?
Ans: For small amplitude sin θ = θ in radians. Then the simple
pendulum has simple harmonic oscillations.
(ix) What is the
relation between 'g' and 'G'? Gin
Ans: g = Gm/R^{2}
(x) What is the value
of 'g' at the centre of the earth?
Ans: zero.
(xi) If you set up a
simple pendulum in an artificial satellite orbiting the earth what will be the
period of the pendulum?
Ans: Inside the satellite g = 0. Hence period is infinite.
(xii) Apparatus of the
Simple Pendulum
Ans: A simple pendulum, stop clock, metre scale, vernier
calipers, stands etc. The simple pendulum consists of a metallic bob suspended
by a light inextensible string passing through the split halves of a cork.
(xiii) Theory of
Simple Pendulum
Ans:The period of a simple pendulum of length l at a place where the acceleration due
to gravity is g, which is given by,
T = 2π √(l/g);
Therefore, g = 4 π^{2} (l/T^{2})
(xiv) Aim of the
Simple Pendulum Experiment
Ans: (a) To determine the acceleration due to gravity at the
place.
(b) To draw l – T^{2}
graph and hence to find the length and period of the Pendulum.
(xv) Procedure of the Simple Pendulum Experiment
(a) To find
the acceleration due to gravity at the place
The period
of oscillation, T = (t/30), is calculated. The experiment is repeated with different
lengths l (60, 70, 80 ………….. cm) of the pendulum. In each case l/T^{2} is
calculated. In all cases it is found that (l/T^{2}) is a constant. The
average value of (l/T^{2}) is determined and the acceleration due to
gravity (g) is calculated. g = 4π^{2}(l/T^{2})
(b) To draw
T^{2} — I graph
The
experiment is performed as explained above. A graph is drawn with l along the
Xaxis and T^{2} along the Yaxis. This graph is a straight line.
(i) To find
the length of the seconds pendulum
A seconds
pendulum is one for which the period of oscillation is 2 seconds. From the
graph the length 1 corresponding to T^{2} = 4 is determined. This gives
the length of the seconds pendulum.
(ii) To
find the length of the pendulum whose period is 1.5 seconds, the length l corresponding
to T^{2} = 1.5^{2} = 2.25 is determined from the graph.
(iii) From
the graph, 1/T^{2} = AB/BC. Therefore, g = 4π^{2}(AB/BC)
The Concurrent Forces Viva Questions and Answers
December 10, 2019

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The Concurrent Forces Viva Questions and Answers
(i) State parallelogram law of forces
Ans: If two forces acting at a point be represented in
magnitude and direction by the adjacent sides of a parallelogram drawn from a
point, the resultant force is represented in magnitude and direction by the
diagonal of the parallelogram drawn from the same point
(ii) State triangle of forces
Ans: If three forces acting at a point can be represented in
magnitude and direction by the sides of a triangle taken in order then the
forces is in equilibrium,
(iii) What is meant by resultant of a set of force?
Ans: It is that single force which effectively replaces the
set of forces
(iv) What are concurrent forces?
Ans: Forces acting at a point are known as concurrent
forces.
(v) What is Lami's theorem?
Ans: If three forces acting at a point keep it in
equilibrium, then each force is proportional to the since of the angle between
the other two.
(vi)
What is the angle between them
Ans: 45°
vii) Will the forces 15N, 20N and 40N acting at a point keep
it in equilibrium?
Ans: No
viii) What are the main sources of error in the experiment?
Ans: (a) Friction at the pulleys. (b) Thread cannot be
weight less.
(ix) If there is a lot of friction at the pulleys in what
way the result of this experiment be affected?
Ans: The forces represented by the hanging weight will have
values lower than what are given by the relation W = mg
(x) Apparatus of Concurrent Forces
Ans: Parallelogram law apparatus consisting of two
frictionless pulleys attached to a framework fixed on the top of a vertical
drawing board, light inextensible strings, weights and weight hangers and the
given body.
(xi) Theory of Concurrent Forces
Ans: If three coplaner concurrent forces P, Q and R keep a
point in equilibrium, the resultant of P and Q will be equal and opposite to R,
the equilibrant.
Physics Experiment's Viva Questions
December 03, 2019

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Some Physics Experiment's Viva Questions
1. The Moment Bar Viva Questions and Answers
1. The Moment Bar Viva Questions and Answers
Ans: The principle of moment. That is, the algebraic sum of
the moment of the forces acting on a rigid body is zero.
(ii) Why do you
suspend the metre scale at the centre of gravity to find the weight of a body?
Ans: In order to make the moment of the weight of the scale
about the point of suspension zero.
(iii) Can you find the
relative density of a body using moment bar.
Ans: Yes
2. The Helical Spring Viva Questions and Answers
(i) Define stress
Ans: It is the normal force acting per unit area.
(ii) State Hookes law
Ans: Within elastic limits stress is proportional to the stain
(iii) What is spring constant?
Ans: F = kx; where k is the spring constant. It is the force required to produce unit extension.
(iv) What are the conditions essential for the motion of a body to be simple harmonic?
Ans:
(a) acceleration is proportional to its distance from the fixed point
(b) acceleration is directed towards a fixed point
(v) What are the factors on which the period of vertical oscillations of a spring depend?
Ans:
(a) Directly proportional to the square root of the mass attached
(b) inversely proportional to the spring constant
(vi) What is the unit of spring constant?
Ans: Nm^{1}
(vii) Which is more elasticsteel wire or rubber wire of the same diameter and length?
Ans: Steel wire
(viii) What is the relation between load and extension?
(ix) What is the spring constant in terms of load (M) and extension (e)
Ans: K = Load / Extension = M/e kg/m = (M/e)gNm^{1}
3. The Friction Viva
Questions
(i) What is meant by friction?
(ii) Explain limiting static friction.
(iii) Distinguish between static friction and dynamic
friction.
(iv) Define coefficient of friction.
(v) What are the factors on which coefficient of friction
depends?
(vi) What is rolling friction?
(vii) Why is friction considered a necessary evil?
(viii) Lubricants reduces friction, how?
4. The Young's Modulus Viva
Questions
(i) Explain the term 'stress' and 'strain"?
(ii) Distinguish between stress and pressure.
(iii) What is meant by elastic limit?
(iv) State Hook's law.
(v) What is the modulus of elasticity?
(vi) What are the different moduli of elasticity?
(vii) Define Young's modulus of a substance.
(viii) What is the unit of modulus of elasticity?
(ix) Why do you use a micrometer or vernier instead of a
metre scale to measure the increase in length of the wire?
(x) What is elastic hysteresis?
5. The Newton's Law of
Cooling Viva Questions
(i) Name the different modes of transmission of heat.
(ii) What is radiation?
(iii) What is Stefan's law?
(iv) Define emissivity (or relative emittance) of a surface.
(v) State Kirchhoff's law.
(vi) Explain Newton's law of cooling.
(vii) What is the velocity of heat radiation?
(viii) To which part of the electromagnetic spectrum do the
thermal radiation belong?
(ix) What is a black body?
(x) What is meant by black body radiation?
(xi) What is Wien's displacement law?
6. The Vernier Calipers
7. The Screw Gauge
8. The Spherometer
9. The Common Balance
10. The Concurrent Forces
11. The Simple Pendulum
12. The Surface Tension
13. The Viscosity
14. The Sonometer
15. The Resonance Column
16. The Inclined Plane
17. The Boyles Law
18. The Jolly's Bulb Apparatus
19. The Ohm's Law
20. The Meter Bridge
21. The Post Office Box
22. The Potentiometer
23. The Figure of Merit of Galvanometer
24. The Conversion of Galvanometer into Ammeter
25. The Conversion of Galvanometer into Voltmeter
26. The Concave Mirror
27. The Convex Lens
28. The Convex Mirror
29. The Concave Lens
30. The Refraction through a Prism
31. The Refractive Index of a Glass Slab Using Travelling Microscope
32. The PN Junction Diode
33. The Zener Diode
34. The Mapping of Magnetic Field
35. The Tangent Galvanometer
36. The Spectrometer
37. The Logic Gates 1 (AND and OR gates)
38. The Logic Gates 2 (NOT gate)
39. The Logic Gates 3 (Using switches)
6. The Vernier Calipers
7. The Screw Gauge
8. The Spherometer
9. The Common Balance
10. The Concurrent Forces
11. The Simple Pendulum
12. The Surface Tension
13. The Viscosity
14. The Sonometer
15. The Resonance Column
16. The Inclined Plane
17. The Boyles Law
18. The Jolly's Bulb Apparatus
19. The Ohm's Law
20. The Meter Bridge
21. The Post Office Box
22. The Potentiometer
23. The Figure of Merit of Galvanometer
24. The Conversion of Galvanometer into Ammeter
25. The Conversion of Galvanometer into Voltmeter
26. The Concave Mirror
27. The Convex Lens
28. The Convex Mirror
29. The Concave Lens
30. The Refraction through a Prism
31. The Refractive Index of a Glass Slab Using Travelling Microscope
32. The PN Junction Diode
33. The Zener Diode
34. The Mapping of Magnetic Field
35. The Tangent Galvanometer
36. The Spectrometer
37. The Logic Gates 1 (AND and OR gates)
38. The Logic Gates 2 (NOT gate)
39. The Logic Gates 3 (Using switches)
Spherometer and Common Balance Viva Questions
December 02, 2019

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Spherometer and Common Balance Viva Questions and Answers
The Spherometer
(i) What is the principle of a spherometer?
Ans: It works on the principle of a micrometer screw.
(ii) Why is the spectrometer called so?
Ans: Since it is used to measure the radius of curvature of
a spherical surface, it is known as spectrometer.
(iii) How will you calculate the least count of a
spherometer?
Ans: LC = Pitch/No. of head scale divisions.
(iv) Is there any zero correction for a spectrometer?
Ans:
No
The common balance
(i) What is the principle of a physical balance?
Ans: It is form of lever of first order and works on the
principle of moments.
(ii) What are the requisites of a good balance?
Ans: Truth, sensibility and stability
(iii) What is a true balance'?
Ans: A balance is true if the beam remains horizontal when
the pans are empty or when they are equally loaded
(iv) What is meant by sensibility of a balance?
Ans: It is the mass required to change the resting point by
one division
(v) What is the function of the plumb line in a balance?
Ans: We can level the balance with the help of the plumb
line so that the beam rotates in a vertical plane
(vi) While weighing, the shutter must be closed. Why?
Ans: This is to avoid disturbance due to air current
(vii) Is it advisable to weigh a hot body?
Ans: No, with hot body convection currents are set up in
air, which disturb the equilibrium.
(viii) What is the difference between mass and weight?
Ans: According to Newton's first law of motion mass is a
measure of the inertia possessed by the body which makes it resist any change
in its state of rest or motion. It is also defined as the quantity of matter
contained in it. Weight of a body is the force with which the earth attracts
the body towards its centre
(ix) What are the S.I. unit of mass and weight?
Ans: Mass—kilogram; Weight—Newton
Screw Gauge Viva Questions and Answers
November 30, 2019

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Screw Gauge Viva
Questions and Answers
Ans: Screw gauge.
(ii) What is meant by pitch of a screw gauge?
Ans: It is the distance advanced by the screw for one
complete rotation of the head.
(iii) The pitch of a screw is 1 mm and the number of
divisions on the head scale is 100. What is the least count?
Ans: Least count =
pitch/ No: of divisions on the head scale = 1/100 = 0.01 mm
(iv) What is zero error of a screw gauge?
Ans: If the zero of the head scale does not coincide with
the zero of the pitch scale when the end of the movable screw is in contact
with the stud, the screw gauge is said to have zero error.
(v) If the zero of the head scale is 5 divisions above the
line of graduation of the pitch scale when the gap is closed, what is the zero
error? What is the zero correction? Least count of the vernier = 0.01 mm
Ans: zero error = 5 x 0.01 = 0.05 mm and zero correction =
+0.05 mm
(vi) If the zero of the head scale is 5 divisions below the
line of graduation of the pitch scale when the gap is closed, what is the zero
error and correction? Least count = 0.01 mm
Ans: zero error = +5 x 0.01 = +0.05 mm and zero correction =
0.05 mm
(vii) Why do we take a number of observations for the
diameter of a wire?
Ans: Even if the wire appears uniform it may not be true. So
to take the average value we take a set of readings
(viii) Why do you stop rotating the screw as soon as the
ratchet begins to turn between the fingers?
Ans: When the ratchet begins to turn, the two faces are in contact
or in contact with the body held between them. The device avoids undue pressure
on the screw.
Vernier Caliper Viva Questions and Answers
November 28, 2019

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Vernier Caliper Viva
Questions and Answers
(vi) Apparatus of Vernier Calipers
Ans: The vernier calipers, the given cylinder and the metallic rectangular block. The vernier calipers consists of a main scale and a small subscale called vernier scale. The main scale is usually graduated in mm. The vernier scale is a subscale which can slide along the main scale and can be fixed at any position with the help of a screw. Usually there will be 10 divisions on the vernier scale which are equivalent to 9 mm on the main scale. The main scale and the vernier scale are provided with jaws at their ends. When the jaws are in contact, the zero of the vernier coincides with the zero of the main scale.
(vii) Theory of Vernier Calipers
Ans: When a body is gripped between the jaws, the main scale reading (M.S.R) is the reading on the main scale just before the zero mark of the vernier scale and the vernier scale reading (V.S.R) is the number of the vernier division which coincides with some division of the main scale.
Ans: It is the smallest measurement that can be made with
the given instrument
(ii) What is meant by
least count of a vernier calipers?
Ans: It is the smallest length that can be measured with the
instrument and it is equal to the difference between a main scale division and
a vernier scale division.
(iii) The least count
of a vernier is 0.001 cm. What is the order upto which it can measure length
accurately?
Ans: It can measure accurately up to 103 cm.
(iv) What part of the
vernier calipers is the vernier scale?
Ans: The sliding scale along the main scale is called
vernier scale.
(v) Which is the
instrument you will use to measure the internal and external diameter of a
tube?
Ans: Vernier calipers
(vi) Apparatus of Vernier Calipers
Ans: The vernier calipers, the given cylinder and the metallic rectangular block. The vernier calipers consists of a main scale and a small subscale called vernier scale. The main scale is usually graduated in mm. The vernier scale is a subscale which can slide along the main scale and can be fixed at any position with the help of a screw. Usually there will be 10 divisions on the vernier scale which are equivalent to 9 mm on the main scale. The main scale and the vernier scale are provided with jaws at their ends. When the jaws are in contact, the zero of the vernier coincides with the zero of the main scale.
(vii) Theory of Vernier Calipers
Ans: When a body is gripped between the jaws, the main scale reading (M.S.R) is the reading on the main scale just before the zero mark of the vernier scale and the vernier scale reading (V.S.R) is the number of the vernier division which coincides with some division of the main scale.
If L. C is the least count of the vernier calipers,
Dimension measured = M.S.R + fraction = M.S.R + (V.S.R x L.C)
Volume of a cylinder = πr^{2}l;
where r is the radius and l is the length of the cylinder.
Volume of the rectangular block = lbh;
where l, b and h are length, breadth and height of the
block.
If r is the internal radius and h is the depth of the
calorimeter,
Internal volume of the calorimeter = πr^{2}h
(viii) Procedure of Vernier Calipers
To find the least count (LC) of the vernier calipers
The least count is the difference between a main scale
division and a vernier scale division. if (n — 1) main scale divisions are
divided into n vernier scale divisions then,
Least count = 1/n x 1 m.s.d
(a) To measure the dimensions of the cylinder
To find the length of the cylinder, it is gripped lengthwise
between the jaws. The main scale reading (M.S.R) immediately before the zero of
the vernier, and the division of the vernier (V.S.R) coinciding with any of the
main scale division are noted.
The length of the cylinder, l = M.S.R. + a fraction = M.S.R.
+ (V.S.R x L.C)
The experiment is repeated by keeping the vernier calipers
at different positions of the cylinder and the average length is calculated.
Similarly the mean diameter of the cylinder is determined.
The radius (r) of the cylinder is calculated from its diameter.
Volume of the cylinder = πr^{2}l
(b) To find the volume of the given rectangular block of
known mass by measuring its dimensions with the vernier calipers and hence to
find its density.
The length (I), breadth (b) and the height (h) of the
rectangular block is determined as in the case of the measurement of the length
of the cylinder.
Volume of the rectangular block, V = l x b x h
If m is the mass of the block, its density, d = m/V
(c) To find the internal radius (r), depth (h) and volume
(V) of the calorimeter.
The upper ends of the jaws are put inside the calorimeter
and open them till each of them touches the inner wall of the calorimeter. The
main scale reading (M.S.R) and the vernier scale reading (V.S.R) are noted. The
inner diameter of the calorimeter = M.S.R + (V.S.R x L.C). The experiment is
repeated keeping the projections of the jaws tightly inside the calorimeter at
different positions and the average diameter is calculated. The inner radius r
of the calorimeter is calculated from its diameter.
The end of the main scale strip is kept on the upper edge of
the calorimeter. The vernier scale is pushed over the main scale till the tip
of the pointer attached to the back of the vernier touches the bottom of the
calorimeter. The M.S.R and V.S.R are noted. The depth h of the calorimeter =
M.S.R + (V.S.R x L.C). The experiment is repeated and the average depth is
calculated.
The volume V of the calorimeter is calculated from the equation,
V = πr^{2}h
Microwave Engineering Viva Questions and Answers
November 27, 2019

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1. Give the range of frequency Band of
Microwave?
Microwaves
are signals in the form of electromagnetic waves with wavelengths ranging from
1m to 1mm. The frequency range of microwaves is from 3 GHz to 300 GHz. The
different frequency range bands are given below.
2. Why the Micro wave got the name as
microwaves?
The
meaning of microwaves is the small waves used for communication. Microwaves can
travel in straight line. So in satellite communication, microwaves are most
commonly used.
3. Discuss in detail about
Electromagnetic Frequency Spectrum?
The different ranges of frequency in
spectrum are given below:
4. List the major advantages of
Microwaves?
The major advantages of microwaves are:
a. Microwave Supports larger bandwidth, so
microwaves are widely used for pointtopoint communications.
b. By using microwaves, it is possible
to attain antenna gain more.
c. Since the bandwidth is more, high
data transmission rates are possible.
d. As the frequency increases, the size
of antenna gets reduced
e. Low power consumption.
f. Effect of fading is less.
g. Gives effective reflection area in
the radar systems.
h. Used in Satellite and terrestrial
communications
i. Effective spectrum usage.
5. List the major applications of Microwaves?
Microwaves
can be used in wide variety of applications like Military, Food industry, radio
astronomy, medical applications, radar, semiconductor processing
techniques, spectroscopy etc.
6. Give the frequency band of Infrared
Rays (IR)?
The range of IR of the visible spectrum
at is from 700 nanometers (nm) to 1 millimeter (mm). This leads to a frequency
range of approximately 430 THz down to 300 GHz.
7. Discuss the band of visible Light?
The frequency band of light is from about
4 × 10^{14} to 8 × 10^{14 }cycles per second, or hertz (Hz) and
wavelengths ranges from 740 nanometers (nm) or 2.9 × 10^{−5} inches, to
380 nm (1.5 × 10^{−5} inches).
8. Mention the band of X Rays?
The frequency band of X rays ranges from10
picometres to 10 nanometres, and the frequencies ranges from 30 petahertz to 30
exahertz (3×10^{16} Hz to 3×10^{19}
Hz).
9. What is the band of gamma Rays?
The frequency range of gamma rays are
from 10^{20}  10^{24} and the wavelength is in the range <
10  12 m
10. Define Phase velocity and Group
velocity?
The
velocity having a wave packet that travels is referred as group velocity. Whereas,
the velocity having the phase of a wave that travels is referred as phase
velocity.
11. The standard frequency used in
Microwave Oven for heating is?
The most modern microwave ovens use a
frequency of 2450 MHz (2.45 GHz) for heating.
12. Give the speed of Electromagnetic
waves in free space?
In free space, the electromagnetic waves
has a speed same as that of light, c = 3 x 10^{8} m/s.
13. Explain about the propagation of EM
waves?
When
an electric charge (q) vibrates, the electromagnetic waves are generated. This generated
wave has both an electric and a magnetic component. Light waves are the example
of EM waves.
14. What is Faraday's law?
Faraday's law is
defined as a current that would be induced in a conductor which is exposed to a
varying magnetic field
15. Define Gauss law?
Gauss's
law is defined as the net flux of an electric field that is closed in an enclosed
surface is directly proportional to the enclosed electric charge.
16. Define Ampere's law?
Ampere’s
law states that “the magnetic field caused
by an electric current would be proportional to the size of electric current having
a constant of proportionality corresponding to the permeability of free space”.
17. Define TEM wave?
Transverse
electromagnetic (TEM) waves are those waves with a mode of propagation of
waves, while the electric and magnetic field lines are transverse (normal wave)
to the direction of propagation.
18. What you understand by Transverse
Electric (TE) wave?
TE
wave is an electromagnetic wave propagating in a medium, including free space,
or any other medium in such a manner that the electric field vector is directed
entirely transverse (perpendicular), to the general forward direction of
propagation.
19. What is mean by Transverse magnetic (TM)
waves?
TM
waves, also known as E waves are characterised by the fact that the magnetic
vector (H vector) is always perpendicular to the direction of propagation.
20. What you understand about EM wave?
Electromagnetic
waves (EM) waves are the type of waves which are created by a result of
vibrations between an electric field and a magnetic field. That is we can say
that the EM waves are composed of oscillating magnetic and electric fields.
21. Discuss about the need of
Transmission line?
The
main use of transmission line is to reduce power loss, dissipated as heat
because of the resistance of the conductors. For long distance power
transmissions, high voltage transmission lines are mostly used.
22. Discuss about the types of
transmission lines?
The different types of transmission
lines are:
a. Wave Guide
b. Fiber Optic
c. Balanced two wire
d. Coaxial cable
e. Microstrip
23. What is single stub matching?
In
order to match any complex load to a transmission line, stub matching is used. Stub
matching is group of shorted or opened segments of the line, which are connected
in parallel or in series with the line at an appropriate distances from the
load.
24. List the main advantages of
microwave integrated circuits (MIC)?
The
main advantages of MIC are:
a.
Many (thousands) of devices can easily be fabricated in a single MMIC at the
same time.
b.
Overall cost of MMIC is less.
c.
Mismatches in the MMIC between components are less.
d.
Since the distances between the components are less, the signal delay is less in
a MMIC.
e.
The wire bond reliability issues are less.
25. Discuss about reflection coefficient?
Reflection coefficient can be defined as
a parameter that describes how much of a wave is reflected by an impedance
discontinuity in the transmission medium. In other words, reflection
coefficient gives the amount of reflected waves in a transmission medium due to
the impedance mismatching.
26. Discuss about the different types of
losses in transmission lines?
The losses occurred in transmission
lines are mainly classified into three types. They are:
a. Copper Losses
b. Dielectric Losses
c. Radiation (Induction) Losses
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