CBSE Class 11-science Answered

i want the list of questions that can be asked in viva on vernier callipers experiment. what level of questions asked and how viva is taken.....plzz tell

Asked by ABHILASHA | 30 Aug, 2019, 07:26: PM

Expert Answer

Qn. 1 :- What is vernier Caliper ? What is its use ?

A vernier caliper is a precision measuring tool, used for three types of measurements,

(i) outside distance (such as the length of an object) ,

(ii) inside distance such as the diameter of a large hole,

(iii) and depth, such as the depth of a hole or the height of a step.
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Qn.2 :- what is vernier scale ?

Vernier scale is the sliding part of vernier caliper. It helps to measure the length accurately.

Accuracy depends on number of divsions in vernier scale.

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Qn.3 :- What is Least Count of vernier Caliper ?

Least Count is either the accuracy of the vernier caliper or the smallest measurement possible by the vernier caliper.

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Qn.4 :- A vernier caliper has 20 divisions. It is found that 20 divisions of vernier caliper coincides with 19 main scale divisions.

What is the least count.

least count = 1 main scale division - 1 vernier scale division

a main scale division = 1 mm

if 20 divisions of vernier scale coincides with 19 divisions, then one vernier scale division = ( 19/20 ) mm

hence least count = 1 -(19/20) = 1/20 mm = 0.05 mm

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Qn. 5 :- How the length is measured ?

(i) leat count of the vernier should be known or it should be calculated by knowing number of main scale divisions

coincided by the number of vernier scale divisions . for example let us say least count is 0.05 mm

(ii) Length of measuring object is kept tightly between two jaws of vernier caliper.

(iii) Main scale reading is taken . for example let us say main scale reading 15 mm

(iv) Vernier scale reading is taken, for example vernier scale reading is 7

( 7th division of vernier coincide with a main scale division )

Hence length = main scale reading + ( vernier scale reading )×(least count) = 15 + (7×0.05) = 15.35 mm

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Qn. 6 :- what is zero error ?

In a perfect vernier caliper , when the two jaws are touched each other,

zero of the main scale should coincide exactly with zero of the vernier scale. In this case there is no zero error.

But in some vernier caliper, zero of the vernier scale is right of zero of the main scale, when the two jaws are touched each other .

In this case we need to find out which number of vernier division coincides with any main scale division.

For example if 3rd division of verneier scale coincide with some main scale division and least count of vernier scale is 0.05 mm,

then zero error is +(3×0.05) = +0.15 mm .

We need to subtract this zero error value after taking measurement with vernier caliper to get the true length.

If zero of the vernier scale is left of zero of main scale, then zero error is -ve.

We need to add this zero error value after taking measurement with vernier caliper to get the true length.

Answered by Thiyagarajan K | 30 Aug, 2019, 10:33: PM

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