Page 21 - Physics - XI

(ii) Measurement of the Thickness of the Sheet
10. Now, insert the given sheet between the screw and stud A. Move the screw by rotating the ratchet till

the sheet is gently gripped between A and B. Stop to move the ratchet when the ratchet slips without
moving the screw.
11. Note the number of divisions of the linear scale visible and uncovered by the edge of the cap. The
reading x is called linear scale reading.
12. Note which number of division on the circular scale (n) is coinciding with the reference line. The
product of n and L.C. gives the circular scale reading.

13. Repeat the steps 10, 11, and 12 for four diff erent positions throughout the surface of the sheet. Record
the observations in a tabular form.
14. Take the mean of the observed thickness of the sheet.

15. Apply zero correction with proper sign to the mean observed thickness to get corrected the thickness
of the sheet.

Observations and Calculations
Determination of the least count of the screw gauge

Number of complete rotations given to the circular scale = a = ______
Distance moved by the screw = b = ______ mm
b
Pitch = = ______ mm
a
Total number of divisions on the circular scale = N = ______

Least count = Pitch = ______ mm
N
Zero error:

(i) ______ mm (ii) ______ mm (iii) ______ mm
Mean zero error = e = ______ mm
Mean zero correction = (– e) = ______ mm

Table for the calculation of diameter d of the wire

S. Reading along any directions (d ) Reading along the perpendicular direction (d )
1
2
No. Linear No. of Circular Diameter Linear No. of Circular Diameter Observed
scale circular scale reading d = x + y scale circular scale d = x + y diameter
1 2 d + d
reading scale y = n × L.C. (mm) reading x scale reading (mm) d i 1 2 2
x divisions (mm) (mm) divisions y = n× L.C.
(mm) coinciding coinciding (mm) (mm)
(n) (n)

1.
2.
3.

4.

19