- AAre mere directions.
- BHave no physical reality.
- CCan be used to indicate the direction of the magnetic field at point.
- DAll the above are correct.
Explanation:
A pictorial representation of magnetic lines of force is very useful in visualizing the strength and direction of the magnetic field. The direction of magnetic lines of force is defined to be the direction in which the north end of a compass needle points. They have no physical existence.
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If identical charges (-q) are placed at each corner of a cube of side b, then electric potential energy of charge (+q) which is placed at centre of the cube will be
|
(a) |
(b) |
(c) |
(d) |
The figure shows a graph between ln
and ln|n|, where
is the area enclosed by the nth orbit in a hydrogen like atom. The correct curve is

|
(a) 4 |
(b) 3 |
(c) 2 |
(d) 1 |
The velocity of light in a medium is half its velocity in air. If ray of light emerges from such a medium into air, the angle of incidence, at which it will be totally internally reflected, is
|
(a) 15o |
(b) 30 o |
(c) 45 o |
(d) 60 o |