Question

How will you find the Zero Error of Vernier Caliper? Explain.

Answer 1

Zero error:

1. Unscrew the slider and move it to the left, such that both the jaws touch each other. Check whether the zero marking of the main scale coincides with that of the Vernier scale.
2. If they are not coinciding with each other, the instrument is said to possess zero error. Zero error may be positive or negative.
3. If the zero mark of the Vernier is shifted to the right, it is called positive error.
4. On the other hand, if the Vernier zero is shifted to the left of the main scale zero marking, then the error is negative.

Positive zero error:

1. From the figure you can see that zero of the vernier scale is shifted to the right of zero of the main scale.
2. In this case the reading will be more than the actual reading.
3. Hence, this error should be corrected. In order to correct this error, find out which vernier division is coinciding with any of the main scale divisions.
4. Here, the fifth vernier division is coinciding with a main scale division.
5. So, positive zero error = +5 × LC = +5 × 0.01 = 0.05 cm.

Negative zero error:

1. You can see that zero of the vernier scale is shifted to the left of the zero of the main scale.
2. So, the obtained reading will be less than the actual reading.
3. To correct this error we should first find which vernier division is coinciding with any of the main scale divisions, as we found in the previous case.
4. In this case, you can see that the sixth line is coinciding. But, to find the negative error, we can count backward (from 10).
5. So, the 4th line is coinciding. Therefore, negative zero error = -4 x LC = -4 x 0.01 = -0.04 cm.