Question

What is negetive and positive zero error in screw gauge?

Answer 1

Positive Zero Error: If the zero mark on the circular scale is below the base line of the main scale, the error is said to be positive. The number of circular scale division which coincides with the base line is multiplied with the least count of the screw gauge to get the positive zero error.

Negative zero error refers to the case when the jaws of the vernier caliper are just closed and the reading is a negative reading away from the actual reading of 0.00mm. If the reading is 0.08mm, the zero error is referred to as +0.08mm.