What are the errors in micrometer screw gauge?

Answer 1

This micrometer has zero error.

The zero marking on the thimble is below the datum line. So this micrometer

has a positive zero error.

In this case we will take the reading on the thimble.

Thimble reading = 0.03 mm

So the micrometer has a zero error of +0.03 mm.

Whatever reading we take on this micrometer we would have to subtract +0.03 mm

The zero marking on the thimble is above the datum line. So this micrometer

has a negative zero error.

In this case we will have to count the number of divisions on the thimble between the zero marking and the datum line.

No. of divisions = 3

Measurement of each division = 0.01mm

So the micrometer has a zero error of -0.03 mm.

Whatever reading we take on this micrometer we would have to subtract -0.03 mm

Answer 2

The micrometer must be checked for any 0 error. There are 2 types of errors in micro meter one is the +ve 0 error while the other is the - ve 0 error. Before placing the object to be measured b/w the anvil and the spindle, turn the thimble until the anvil and the spindle meet. If the 0 mark on the thimble scale lies directly opposite the datum line of the main scale, we say that there is no 0 error. But if 0 goes down the datum line it is known as +ve 0 error ,similarly. when 0 goes up from the datum line it is known as -ve 0 error.

To make your reading pure from error;

• subtract the 0 error from the total reading, if it is +ve error.
• add the 0 error in the total reading ,if it is -ve error.