National Standard Examination in Physics (NSEP) Solved Paper 2016 Part-3

Q: 7. The critical angle between a certain transparent medium and air is . A ray of light traveling through air enters the medium at an angle of incidence equal to its polarizing angle θ. Therefore, the angle of refraction is.

(A)

(B)

(C)

(D)

Q: 8. If a copper wire is stretched to make its radius decrease by , the percentage change in its resistance is approximately.

(A)

(B)

(C)

(D)

Q: 9. Consider a manual camera with a lens having a focal length of 5 cm. It is focused at infinity. For catching the picture of an object at a distance of 30 cm, one would

(A) Move the lens out by about 1 cm

(B) Move the lens out by about 5 cm

(C) Move the lens in by about 1 cm

(D) Find it impossible to catch the picture

Q: 10. Initially interference is observed with the entire experimental set up inside a chamber filled with air, Now the chamber is evacuated. With the same source of light used, a careful observer will find that

(A) The interference pattern is almost absent as it is very much diffused

(B) There is no change in the interference pattern

(C) The fringe width is slightly decreased

(D) The fringe width is slightly increased

Q: 11. Two identical loudspeakers, placed close to each other inside a room, are supplied with the same sinusoidal voltage. One can imagine a pattern around the loudspeakers with areas of increased and decreased sound intensity alternately located. Which of the following actions will NOT change the locations of these areas?

(A) Moving one of the speakers

(B) Changing the amplitude of the signal voltage

(B) Changing the frequency of the signal voltage

(D) Replacing the air in the room with a different gas