Question

What is backlash error and why is it caused?
A. Backlash is the error in motion that occurs when gears change direction.
B. Backlash is the error in reading that occurs due to the least count of instruments.
C. Backlash is the error in reading that occurs due to zero error of instrument.
D. None of the above.

Answer 1

Backlash error can be seen in instruments with internal gears. There may be some slipping between the gears which cause this type of error in an instrument. The best and obvious way to avoid backlash error is to move it in a single direction while making a measurement.

Complete answer:
Backlash error: Certain measurement instruments such as screw gauge use gears internally for their working. However, the most common problem associated with such instruments is backlash error.
Backlash error happens when gears wear out due to continuous use and there is some slipping between the gears. Thus, when we rotate the screw, the gears do not move immediately and thus produce a false increment or decrement in the reading on the scale. This can also be seen when we try to reverse the direction of the movement of the screw, but the screw does not move instantly and there is a lag which produces backlash error.
The most effective way to avoid backlash error would be to move the instrument in a single direction while making the measurement. The error can also be minimized by rotating the screw slowly.

Therefore, the correct option is (A).

Note:
Continuously changing the direction of the movement of gears while making a measurement can lead to a huge amount of backlash error. The movement of gear must be kept in mind and the measurement should be repeated if the direction is needed to be reversed for some reason. New instruments should be used to avoid backlash error.