- AElectric Force.
- BMagnetic Force.
- CElectromagnetic faoce.
- Dgravitational force.
Explanation:
The force which attracts objects like iron is called magnetic force.
The force of attraction or repulsion which are present between two magnetic materials is known as magnetic force iron is a ferromagnetic materials.
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The decay constant of a radioactive element is 1.5
per second. Its mean life in seconds will be
|
(a) 1.5 |
(b) 4.62 |
(c) 6.67 |
(d) 10.35 |
The horizontal component of the earth's magnetic field is 0.22 Gauss and total magnetic field is 0.4 Gauss. The angle of dip. is
|
(a) |
(b) |
(c) |
(d) |
It is desired to photograph the image of an object placed at a distance of 3m from the plane mirror. The camera which is at a distance of 4.5 m from the mirror should be focussed for a distance of
| (a) 3m | (b) 4.5m | (c) 6m | (d) 7.5 m |
The wavelength 21 cm emitted by atomic hydrogen in interstellar space belongs to
|
(a) Radio waves |
(b) Infrared waves |
(c) Microwaves |
(d) g-rays |
Wave is associated with matter
|
(a) When it is stationary |
|
(b) When it is in motion with the velocity of light only |
|
(c) When it is in motion with any velocity |
|
(d) None of the above |
The shortest wavelength of X-rays emitted from an X-ray tube depends on the
|
(a) Current in the tube |
(b) Voltage applied to the tube |
|
(c) Nature of gas in the tube |
(d) Atomic number of target material |