What is the backlash error? How do you reduce it ?

Hint:To answer this question, we first need to understand what is error. The discrepancy between the real or true value and the measured value is defined as an error.The difference between an error and a mistake is that the mistake can be avoided, whereas the error cannot be avoided but can be lessened (minimized).

Complete answer:
Backlash error: The backlash mistake is a motion error that arises when changing the direction of gears. It occurs when the following face of the driving tooth and the leading face of the tooth behind the driven gear are separated. By turning the gear in the same direction, you can avoid this.

Reduction of backlash error:
-By forcing the gear into the mesh more firmly, the space between the centres of a pair of gears is reduced.
-Backlash error refers to the error generated by gears jamming together and making contact on both sides of the screw or gears at the same time.
-Backlash in screw gauges can be avoided by carefully spinning the screw in one direction.
-Backlash error occurs when the tip of the screw does not start moving immediately after reversing the direction of rotation of the thimble owing to wear and tear of the screw thread.

Note:Any sign that a measuring system delivers a misleading reading when the true value of a measured quantity is zero, such as an ammeter needle failing to return to zero when there is no current flowing. A systematic uncertainty may come from a zero error.