Question

(i) In Searle’s experiment, after every step of loading, one waits for sometimes (2 or 3 min.) before taking reading.
(ii)In this duration, the wire becomes free from kinks.
A) Both (i) and (ii) are true and (ii) is the reason for (i).
B) Both (i) and (ii) are true but (ii) is not the reason for (i).
C) Only (i) is true.
D) Only (ii) is true.

Answer 1

Hint:Searle’s experiment is used for the measurement of the young’s modulus. The ratio of normal stress and strain is defined as the young’s modulus of elasticity and it is measured by the use of Searle's experiment.

Complete step by step solution:
In Searle’s experiment there are metal rods and dead weight is used. The dead weight is hung onto the metallic rod and we wait for the sometime around 2 to 3 min. for the wire to become free from kinks after that the reading of the change in length is taken and longitudinal strain is calculated also using the weight of the dead load the weight of the dead load is calculated. Now due to change in the length of the metal wire there is change in the diameter and the cross sectional area is also calculated, the young’s modulus is calculated as the ratio of normal stress and longitudinal strain and by placing the values we get the young’s modulus. In Searle's experiment after every step we wait for 2 or 3 min. so that the wire becomes free from kinks so the statement (ii) is the correct reason for (i) statement.
Correct answer for this problem is option A.

Note: Normal stress is defined as the ratio of weight of the body to the area of cross section and longitudinal strain is defined as the ratio of the change in length to the original length of the metallic wire. The weight is the product of mass and acceleration due to gravity.