Force between two identical bar magnets whose centres are r metre apart is 4.8 N, when their axes are in the same line. If separation is increased to 2r, the force between them is reduced to
|
(a) 2.4N |
(b) 1.2N |
(c) 0.6N |
(d) 0.3N |
(d) 0.3N
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
A long solenoid has 200 turns per cm and carries a current of 2.5 amps. The magnetic field at its centre is (
|
(a) 3.14 |
(b) 6.28 |
|
(c) 9.42 |
(d) 12.56 |
Under which of the following conditions will a convex mirror of focal length f produce an image that is erect, diminished and virtual
|
(a) Only when 2f > u > f |
(b) Only when u = f |
|
(c) Only when u < f |
(d) Always |
Continuous spectrum is not due to
|
(a) Hydrogen flame |
(b) Electric bulb |
|
(c) Kerosene oil lamp flame |
(d) Candle flame |
The focal length of the objective of a compound microscope is:
