Vernier Caliper Viva Questions and Answers

(i) What is meant by least count of an instrument?

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 10-3 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) What is vernier? Why is it so named?

Vernier is a device for measuring small lengths accurately, correct upto a fraction of a millimetre. It is so named as it was devised by a French Mathematician, Paul Vernier.

(vii). State three uses of a vernier calipers.

(i) To measure length of small object

(ii) To measure internal diameter of beaker.

(iii) To determine surface area and volume of sphere.

(viii) Name the instrument you could use for the measurement of internal and external diameter of a beaker.

Vernier calipers.

(ix) What is meant by least count of a measuring instrument?

The smallest value of physical quantity which can be measured accurately by the instrument.

(x) What is a vernier constant?

It is the difference between a main scale division and a vernier scale division.

(xi) What is meant by zero error of vernier calipers?

On bringing the jaws of vernier calipers in contact with each other, some times the zero of the vernier scale may not coincide with the zero of the main scale. Thus the vernier calipers is said to possess zero error.

(xii) How does zero error creep in this instrument?

It is due to (i) wear and tear on account of the long use of the instrument, (ii) manufacturing defect.

(xiii) What is the function of the upper jaws of the vernier calipers?

The function of the upper jaws of the vernier calipers is to measure the internal dimensions of hollow objects.

(xiv) 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 sub-scale 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.

(xv) 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 = πr2l;

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 = πr2h

(xvi) 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 = πr2l

(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 = πr2h