- A2.8A.
- BAbout 2A.
- C1.4A.
- DUndefined for a direct current.
Explanation:
A constant current exists in a resistor is rms current it is equal to 2.8Amp.
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A caesium photocell, with a steady potential difference of 60V across, is illuminated by a bright point source of light 50 cm away. When the same light is placed 1m away the photoelectrons emitted from the cell
|
(a) Are one quarter as numerous |
|
(b) Are half as numerous |
|
(c) Each carry one quarter of their previous momentum |
|
(d) Each carry one quarter of their previous energy |
A bi-convex lens made of glass (refractive index 1.5) is put in a liquid of refractive index 1.7. Its focal length will
|
(a) Decrease and change sign |
|
(b) Increase and change sign |
|
(c) Decrease and remain of the same sign |
|
(d) Increase and remain of the same sign |
A beam of electron is used in an YDSE experiment. The slit width is d. When the velocity of electron is increased, then
|
(a) No interference is observed |
(b) Fringe width increases |
|
(c) Fringe width decreases |
(d) Fringe width remains same |
A point source of light B is placed at a distance L in front of the centre of a mirror of width d hung vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror at a distance 2L from it as shown. The greatest distance over which he can see the image of the light source in the mirror is

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(a) d/2 |
(b) d |
(c) 2d |
(d) 3d |
The current in a coil changes from 4 ampere to zero in 0.1 s. If the average e.m.f. induced is 100 volt, what is the self inductance of the coil
|
(a) 2.5 H |
(b) 25 H |
(c) 400 H |
(d) 40 H |

A pencil dipped partially in water appears bent because of:
Two circuits have coefficient of mutual induction of 0.09 henry. Average e.m.f. induced in the secondary by a change of current from 0 to 20 ampere in 0.006 second in the primary will be
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(a) 120 V |
(b) 80 V |
(c) 200 V |
(d) 300 V |