Question

Define the terms pitch and least count.

Answer 1

Hint: The given question can easily be defined if we know about the various techniques and instruments used for the measurement of different quantities. Pitch and least count are the values that are considered while taking the measurement from the instruments used to measure an object of very small size.

Complete solution:
We know that for measuring accurate and precise values, we use different types of measuring instruments. Screw gauge, vernier caliper, spherometer are the examples of such instruments which give more accurate and precise values while measuring a quantity. Each of these instruments has its different pitch and least count.
Now, let us define the pitch of an instrument.
Pitch: It is defined as the linear distance covered by the screw in each rotation. In other words, it can be defined as the axial distance between the two threads of the main scale. Mathematically, we can write it as, Pitch = Unit of main scale/No. of divisions in unit
Also, let us define the least count of an instrument.
Least count: It is defined as the smallest value that can be measured by the help of an instrument. Least count is different for different instruments. We can write it as,
Least count = Pitch/No of divisions of circular scale

Hence, we have defined the terms pitch and least count.

Note: Pitch and least count are associated with the instruments used for measuring very small but more accurate values. All these instruments have two measuring scales; one is the main scale and the other is the precise scale. For vernier calipers this precise scale is known as vernier scale, for screw gauge it is known as micrometer.