Electric potential is given by 
T, hen electric force acting on 2C point charge placed on origin will be
|
(a) 2N |
(b) 6N |
(c) 8N |
(d) 20 N |
(d) 20 N
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The work function for tungsten and sodium are 4.5 eV and 2.3 eV respectively. If the threshold wavelength λ for sodium is 
, the value of λ for tungsten is
|
(a) 5893 Å |
(b) 10683 Å |
(c) 2791 Å |
(d) 528 Å |
If the energy of the photon is increased by a factor of 4, then its momentum
|
(a) Does not change |
(b) Decreases by a factor of 4 |
|
(c) Increases by a factor of 4 |
(d) Decreases by a factor of 2 |
X-rays are not used for radar purpose because
| (a) They are not reflected by the target |
| (b) They are not electromagnetic waves |
| (c) They are completely absorbed by the air |
| (d) They sometimes damage the target |
A convex lens of focal length f is placed somewhere in between an object and a screen. The distance between the object and the screen is x. If the numerical value of the magnification produced by the lens is m, then the focal length of the lens is
|
(a) |
(b) |
(c) |
(d) |
