Page 93 - Physics - XI

observations, the micrometer screw should move in downward direction only so that the backlash error
can be avoided.

9. Find the mean reading for each load and calculate the extension for 2.0 kg by subtracting the fi rst
reading from fi fth, second from sixth, and so on. Find the mean extension for 2.0 kgf. Record all the
observations in the observation table.

Observations
(a) Measurement of the diameter of the wire

Pitch of the screw gauge = ______ cm

Number of divisions on circular scale = N = ______

Least count of the screw gauge = Pitch = ______ cm
N
Zero correction = ______ cm

Table for calculation of the diameter of the wire

S. Reading along the AB direction Reading along the perpendicular direction CD Mean
No. Linear Circular Observed Linear Circular Observed diameter observed

scale scale diameter scale Scale d = M′ + n′ × L.C. diameter
d
d +
2
reading reading d = M + n × L.C. reading Reading (cm) d = 1 2 2
0
1
M (cm) n (cm) M′ (cm) n′
(cm)
1.
2.
3.

4.
5.

6.

Mean corrected diameter = d = d + zero correction = ______ cm
0
d
Mean radius = r = = ______ cm = ______ m
2
(b) Measurement for extension l of the wire
Length of the wire = L = ______ cm = ______ m

Pitch of the micrometer screw = ______ cm

No. of divisions on the circular disc = N = ______

Least count of micrometer screw = Pitch = ______ cm
N
Breaking stress for wire = ______ N/m 2

1 2
rd of the breaking stress = ______ N/m
3

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