Investigatory Project in Physics for Class 11
INVESTIGATORY
PROJECT – 1
THE
DEVIATION FROM OHM'S LAW
Aim: To study the deviation from ohm's
law due to the change of temperature of the conductor.
Materials
and apparatus
(i) A
resistance wire (of resistance about 1 Ω) connected
between two terminals which are fixed on a wooden strip.
(ii)
Sensitive ammeter of range about 3A
(iii)
Digital voltmeter
(iv)
Rheostat
(v) Battery
eliminator
(iv) Key
etc
Procedure
Connections
are made as shown in the figure. The current I and p.d across the resistance R
are measured. V/I is calculated. Sufficient current is sent through the
resistor by adjusting the rheostat so that it is heated. V/I is calculated. The
experiment is repeated for different values of current. It is seen that V/I is
not a constant and it increases with the increase in current.
INVESTIGATORY
PROJECT – 2
THE SELF
INDUCTION
Aim: This is a project to study the
process of self induction.
Material
required
(i) 6V
torch bulb
(ii) 3-0-3,
500 mA transformer
(iii) A
piece of PVC pipe
(iv) A
wooden plank or card board piece
(v)
Connecting wire
(vi) 22
gauge finely insulated copper wire about 100 gram
(vii) iron
pieces
Procedure
Fix the transformer on the wooden plank. Connect the wires from the output of the transformer to the bulb. The middle wire should not be used. Wind about 450 turns of the copper wire on the PVC pipe and fit it on the board. The end B of the solenoid is connected to the bulb. Connect wires from P to C and from R to B. Apply 230 V ac mains to transformer. The voltage gets stepped down to 6V. The bulb glows. Disconnect the wire from R to B and connect it to the point A. The bulb will become dim. The ac when passed through the solenoid creates changing flux which induces the back end. Then the bulb becomes dim. If soft iron bars are introduced into the PVC pipe, the back emf increases due to increased flux density. Hence the effective voltage decreases and the bulb will become dimmer.
INVESTIGATORY
PROJECT – 3
THE
ELECTROMAGNETIC INDUCTION
Aim: This is a project meant to study
electromagnetic induction.
Materials
needed
(1) Finely
insulated copper wire of gauge 24 about 100 gram
(ii) A
piece of GI pipe
(iii) Magnet
from a loud speaker
(iv) Two
LEDs preferably of different colours.
Procedure
Wind about
450 turns of copper wire on the GI pipe and attach the two LEDs at the ends of
the wire in such a way that they are in opposite directions. Move a magnet to
and fro inside (or near) the coil very quickly. The coil will experience a
change of flux. Hence an emf will be induced and current will flow. The LED
will glow indicating the presence of current. When the magnet moves upward one
LED will glow but when the magnet is made to move in the downward direction, the
other LED will glow. This indicates that the current is reversing direction
i.e., it is AC.
INVESTIGATORY
PROJECT – 4
The IMPROVISED RESONANCE COLUMN
Aim: This project is meant to show resonance and to
calculate the velocity of sound in air.
Materials
needed
(i) A fused
tube light
(ii) Tube
of a cycle tyre
(iii) A
stand
(iv) A
tuning fork and a rubber hammer
Procedure
Both the ends of a fused tube light are carefully cut open. The inside surface of the tube is washed to remove the coating. Thus we get a tall glass tube for the resonance column. The glass tube is clamped vertically on a stand. A long cycle tube with both ends open is taken. One end of the tube is slipped on to the lower end of the glass tube. The other end of the rubber tube is closed by tying the end with a thread. The rubber tube is rolled up.
The glass
tube is filled with water. An excited tuning fork of frequency f is kept
horizontally over the mouth of the glass tube. The rubber tube is slowly
unrolled so that the water level in the glass tube is slowly lowered and length
of the air column inside the tube gradually increased till a booming sound is
heard. Now the air column vibrates in resonance with the tuning fork. The
length l of the air column is measured. The velocity v of sound at room
temperature is calculated using the equation,
V = 4lf
INVESTIGATORY
PROJECT – 5
THE
BIASING OF A TRANSISTOR
You all
know that the transistor is known as wonder child of electronics. This is a
project to realize that a transistor work only when its emitter junction is
forward biased and collector junction is reverse biased.
Materials
needed
(i) A one kΩ resistor
(ii) A
transistor - AD 149
(iii) A 6V
bulb
(iv)
Connectng wires
(v) 1.5 V
torch cell
Procedure
Connect the
resistor, transistor and bulb as shown in the figure. The transistor is PNP.
Now apply 1.5 volt dc with positive at A and negative at B. The bulb glows. Now
the emitter junction is forward biased and collector junction is reverse
biased. Hence the transistor conducts. If the voltage is reversed the emitter
junction will be reverse biased. Hence the transistor will not conduct. The
bulb will not glow.
INVESTIGATORY
PROJECT – 6
THE
PULSE AMPLIFIER
Aim: This is a project meant to show the
amplification.
Materials
required
(i)
Transistors BC 548, BC 558
(ii) LED
(iii) 100Ω resistor
Procedure
Arrange the
devices as shown in the circuit. Our body has a small voltage. At the point A
you touch with the finger. The body voltage is applied at the base. In the
first transistor this voltage gets amplified and the output goes as input of
the second transistor. Reamplification takes place. Output makes the LED glow.
When we take off the hand from the base the whole process stops.
When the
base of the first transistor BC 548 is touched the body voltage makes the base
emitter junction forward biased. The transistor conducts and its amplified
output is fed as the input of the second transistor BC 558. The second
transistor amplifies its input and the amplified output makes the LED glow.
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About Sreejith Hrishikesan
Sreejith Hrishikesan Nair is a M-Tech graduate in Communication Systems. He completed B-tech Degree in Electronics and Communication.He is a person who wants to implement new ideas in the field of Technology.
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