Aim:
To determine Young’s modulus of elasticity of the material of a given wire by Searle’s method.
Procedure:
i. Arrange the experimental set up as shown in diagram. Attach a zero load (slotted hanger it
self) and dead load (E) to the frames of the experimental wire and dummy wire respectively so
that the wires become free of kinks and remain vertically straight.
ii. With the help of micrometer screw gauge, find the correct diameter of the wire at three
different places. At every place two readings of the micrometer are taken while holding it in
one position and another perpendicular to it by rotating through 90°.
iii. In all, six readings of the diameter of the wire are taken. Hence mean diameter and radius of
the wire is found out.
iv. Adjust the spirit level so that the air bubble is at the centre. Note down the reading of the
micrometer screw (M) attached to it. This is zero reading. (This contains main scale reading
and circular scale reading.)
v. Using a meter scale measure the length L of the experimental wire (A) from the point of
suspension to the point fixed on the frame.
vi. Add half kg weight to experimental wire, wait for two minutes. Bring the air bubble in the
Spirit level at the centre. Note the main scale and circular scale reading of the micrometer (M)
of searle’s apparatus.
Repeat the above procedure, each time by adding half kg weight to the hanger.
vii. Take six readings for six different weights. Care should be taken that elastic limit is not
crossed.
viii. Decrease the load in same steps of half kg weight and note the corresponding reading for a
given load for unloading. Find the mean of the two readings corresponding to loading and
unloading.
ix. Find the extension (elongation) produced in the wire for every load.
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