Question

The vernier scale used for measurement has a positive zero error of $0.2$ mm. If while taking a measurement it was noted that 'o' on the vernier scale lies between $8.5$ cm and $8.6$ cm, vernier coincidence is $6$, then the correct value of the measurement in cm is. (least count = $0.01cm)$

• A. $8.36cm$
• B. $8.56$
• C. $8.58cm$
• D. $8.54cm$

Answer 1

The correct option is D

$8.54cm$

The explanation for the correct answer:-

In the case of option D.

Step 1: Given data

Positive zero error = $0.2mm$.

Main scale reading = $8.5cm$

Step 2: Formula used

We know, $Finalreading=MSR+(VSD\times LC)-zeroerror$

Where MSR = main scale reading, VSD = vernier scale division, LC = least count,

Step 3: Calculating final reading

Putting all the known values in the above formula, we get

$Finalreading=MSR+(VSD\times LC)-zeroerror$

Final reading = $8.5+\left(6\times 0.01\right)-0.02=8.5+0.04$

$=8.54cm$

The explanation for the incorrect answer:-

Option (a) $8.36cm$

1. The vernier scale takes precise measurements.
2. It contains two scales: a regular, huge scale (the main scale) and a smaller scale inside that is used to accurately compute measurements.
3. Option is incorrect

Option (b)$8.56$

1. Due to the vernier acuity idea upon which it is built, the vernier scale provides accurate measurement.
2. The misalignment of two line segments is measured by the vernier acuity, a form of visual acuity.
3. Option is incorrect

Option (c) $8.58cm$

1. Aligned and misaligned lines are easily distinguishable by the human eye.
2. Although some calipers measure in both metric and imperial units, the vernier caliper typically only displays measurements in one.
3. Option is incorrect
4. Therefore option d is the correct answer

Therefore, option (D) is the correct answer.