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SPHEROMETER Q.1: Why the instrument is given the name “spherometer”? Ans. Because it is used to determine the radius of curvature of a spherical surface. Q.2: What is the pitch of a spherometer? Ans. The distance covered by the circular disc in one complete rotation along the main scale. Mostly pitch of spherometer = 1 mm = 0.1 cm. Q.3: How do you find the least count of spherometer? Ans. L.C. of spherometer = (Pitch of screw / No. of divisions an circular scale) = (0.1 cm / 100) = 0.001 cm. Q.4: What is meant by ‘radius of curvature’ of a surface? Ans. The radius of that sphere from which the surface is cut. Q.5: What is the radius of curvature of plane surface? Ans. Infinite. Q.6: Is paper insertion method for testing the touching position of the screw is correct? Ans. No, because the thickness of ordinary paper (0.01 cm) is greater than the L.C. Q.7: Is there any zero error in a spherometer? Ans. Spherometer may have a zero error. Z.E. in spherometer =...

MICROMETER SCREW GAUGE Q.1: What is a screw? Ans. Screw is a simple machine related to inclined plane. Q.2: What is meant by “gauge”? Ans. The gauge means device or instrument. Q.3: Name two main parts of a screw-gauge? Ans. (a) A nut (b) A bolt or screw Q.4: What is meant by pitch of a screw? Ans. Pitch is the distance between two nearest (consecutive or successive) threads along the axis of screw. Q.5: How is the pitch found? Ans. By dividing the distance covered by the screw in a known number of rotations by the total number of relations. Q.6: What is the least count (L.C.) of the screw gauge? Ans. L.C. of screw gauge = 0.001 cm. Q.7: How the L.C. of a screw gauge is found? Ans. By using the relation: L.C. = (Pitch of the screw / No. of circular scale divisions) Q.8: What is meant by zero error of a screw-gauge? Ans. The error which arises when the zero of circular scale does not coincide with the zero of the main scale upon joining the two studs. ...

VERNIER CALIPER Q.1: What is vernier calipers? Ans. It is simple instrument by which length of an object can be measured accurately up to one-tenth of a millimeter or one-hundredth of a centimeter. Q.2: What is the use of Vernier Scale? Ans. To increase the accuracy of the main scale. Q.3: What is least count (L.C.)? Ans. The minimum measurement that can be taken by an instrument. Q.4: What is the least count of? meter scale (b) Stop Watch (c) Vernier Calliper Ans. The least count of: meter scale = 0.1 cm or 1 mm. stop watch = 0.01 sec or 1/100 sec. or according to stop watch. vernier scale = 0.002 mm or 0.01 mm according to Vernier calliper Q.5: What are units of vernier scale? Ans. Vernier has not units of its own. Q.6: What is the difference in the measurement of one smaller division on the main scale (M.S.) and that of vernier scale (V.S.) Ans. (1 smallest Div. on M.S.) – (1 smallest Div. on V.S) = 0.1 – 0.09 = 0.01 cm = Least count. Q.7: How th...

                                             NUMERICAL PROBLEMS 1       The wavelength of yellow light in air is 5.8×10 -7 m. Calculate its wavelength in diamond of refractive index 2.4                                                 Ans: 2.41×10 -7 m 2.       Light passes through a single crystal of ruby 25 m long and emerges with a wavelength of 6.4×10 -7 m . If the refractive index of ruby is 1.6, calculate the number of wavelengths inside the crystal.                                           ...