Page 38 - Physics - XI

Q7. Which of the instruments gives the most precise result if the length of an object is measured:

a. Measuring tape b. Metre rule c. Vernier Callipers d. Screw gauge

Q8. When the zero of the circular scale of a screw gauge coincides with the zero of the main scale
before A and B comes in contact, then the instrument has

A B

a. Positive zero error b. Negative zero error c. No zero error d. Can't be said anything

Q9. Two full turns of the circular scale of a screw gauge cover a distance of 1 mm on its main scale.
The total number of divisions on the circular scale is 50. Further, it is found that the screw
gauge has a zero error of – 0.03 mm. While measuring the diameter of a thin wire, a student
notes the main scale reading of 3 mm and the number of circular scale divisions in line with
the main scale as 35. The diameter of the wire is

a. 3.32 mm b. 3.73 mm c. 3.67 mm d. 3.38 mm
Q10. The distance moved by the screw along its axis in one complete rotation of its head is
a. pitch b. least count c. measurement d. not

Q11. A screw gauge has the least count of 0.01 mm and there are 50 divisions in its circular scale.
The pitch of the screw gauge is

a. 0.5 mm b. 1.0 mm c. 0.01 mm d. 0.25 mm
Q12. What is the smallest dimension that a laboratory screw gauge can measure?
a. 0.1 mm b. 0.01 mm c. 0.1 cm d. 0.01 cm

Q13. An experiment is conducted to measure the thickness of a thin sheet using a screw gauge. The
main scale reading is 2 mm, and the circular scale reading is 25. The pitch of the screw gauge
is 0.5 mm, and the least count of the instrument is 0.01 mm. The thickness of the thin sheet is

a. 1.125 mm b. 2.00 mm c. 11.25 mm d. 112.5 mm
Q14. Which measuring instrument consists of a metal triangular frame supported on three legs,
used to measure the radius of curvature of an object such as lenses and curved mirrors that
are spherical?

a. Viscometer b. Spherometer c. Vernier Calliper d. Screw gauge
Q15. If h is the elevation or depression of a spherical surface from the plane glass plate and c be the

mean distance between two consecutive points corresponding to the impressions made by the
three legs of a spherometer, then the radius of curvature is
c 2 h c 2 h 2 c 2 h c 2
a. − b. + c. + d. + 2
6 h 2 6 h 2 6 h 2 6 h h

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