Question

what is meant by zero error of a
vernier callipers? How is it determined?

Answer 1

when the zero mark of vernier scale and main scale is not conciding .

Answer 2

Zero error is seen when the zero of the vernier scale doesn't coincide with the zero of the main scale.
There are two types of zero errors.
Positive zero error: When the zero of vernier is to the right of the zero of main scale.
Negative zero error: When the zero of vernier is to the left of the zero of the main scale.

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