# Spherometer and Common Balance Viva Questions

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 pos-sessed 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