Two mirrors at an angle 0° produce 5 images of a point. The number of images produced when θ is decreased to θ − 30° is
9
10
11
12
The radius of the light circle observed by a fish at a depth of 12 m is (refractive index of water = 4/3)
In Young's double slit experiment, the fringe width is β. If the entire arrangement is placed in a liquid of refractive index n, the fringe width becomes
nβ
A plano-convex lens (f = 20 cm) is silvered at plane surface. Now focal length will be
20 cm
40 cm
30 cm
10 cm
The light beams of intensities in the ratio of 9 : 1 are allowed to interfere. What will be the ratio of the intensities of maxima and minima ?
3 : 1
4 : 1
25 : 9
81 : 1
B.
4 : 1
The light beams with intensities being in the ratio , so the amplitudes are ratio . So, the maximum and minimum intensities are in the ratio .
If x1 be the size of the magnified image and x2 the size of the diminished image in Lens Displacement Method, then the size of the object is
x1x2
x12x2
x1x22
In a common emitter configuration, a transistor has β = 50 and input resistance 1 kΩ. If the peak value of AC input is 0.01 V, then the peak value of collector current is
0.01 µA
0.25 µA
100 µA
500 µA
Half-life of a radioactive substance is 20 min. The time between 20% and 80% decay will be
20 min
30 min
40 min
25 min
The energy released by the fission of one uranium atom is 200 MeV. The number of fissions per second required to produce 3.2 W of power is (Take, 1eV = 1.6 x 10-19 J)
107
1010
1015
1011