Question

The zero error of a Vernier is +1. Its zero correction is (take L.C.= 0.01 cm)
A. 0.2 cm
B. -0.2 cm
C. -0.02 cm
D. +0.02 cm

Answer 1

Hint: When the zero on the main scale does not coincide with the zero on the Vernier scale then it is known as Zero error for Vernier. The smallest value the Verner can measure is known as Least count. Zero error correction depends on the least count of the instrument as well as on the zero error. To calculate the zero correction of the Vernier, multiply the least count with the zero error. But, the zero error is positive so take the negate of the product of least count and zero error. This obtained value will be the zero correction.

Complete answer:

Given: Least Count (L.C.)= 0.01 cm
Zero error (Z)= +1
Zero Correction is given by,
$Correction= -(L.C. \times Z) cm$
Substituting values in above equation we get,
$Correction= -(0.01 \times 1) cm$
$\Rightarrow Correction= -0.01 cm$
Hence, the zero correction is -0.01 cm.
So, the correct answer does not match the given options.

Note:
There are two types of zero error namely positive zero error and negative zero error. When the main scale coincides with a number greater than zero on the Vernier scale then it is positive zero error and if it coincides with a number lower than the zero then it is a negative zero error. Students must understand that the least count of typical Vernier calipers are the same but the zero error does not remain the same. Sometimes, there might be no zero error in the instrument. Students must also keep in mind that when the zero error is positive, it is subtracted from the total reading and if it is negative then it is added.