A photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed 
away, the number of electrons emitted by photo cathode would
|
(a) Decrease by a factor of 2 |
(b) Increase by a factor of 2 |
|
(c) Decrease by a factor of 4 |
(d) Increase by a factor of 4 |
(d) Increase by a factor of 4
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In an interference experiment, the spacing between successive maxima or minima is (Where the symbols have their usual meanings)
|
(a) |
(b) |
(c) |
(d) |
Two coherent light sources S1 and S2 (l= 6000 Å) are 1mm apart from each other. The screen is placed at a distance of 25 cm from the sources. The width of the fringes on the screen should be
|
(a) 0.015 cm |
(b) 0.025 cm |
(c) 0.010 cm |
(d) 0.030 cm |
An achromatic combination of lenses is formed by joining
|
(a) 2 convex lenses |
(b) 2 concave lenses |
|
(c) 1 convex lens and 1 concave lens |
(d) Convex lens and plane mirror |
A charge of 10 e.s.u. is placed at a distance of 2 cm from a charge of 40 e.s.u. and 4 cm from another charge of 20 e.s.u. The potential energy of the charge 10 e.s.u. is (in ergs)
|
(a) 87.5 |
(b) 112.5 |
(c) 150 |
(d) 250 |
