- AElectromagnetic
- BCurrent electricity
- CElectrochemical
- DElectrostatic
Explanation:
Lightning is a sudden electrostatic discharge during an electrical storm between electrically charged regions of a cloud, between that cloud and another cloud, or between a cloud and the ground.
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The half life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min will be
|
(a) 93.75% |
(b) 75% |
(c) 25% |
(d) 6.25% |
If the electric flux entering and leaving an enclosed surface respectively is
and
the electric charge inside the surface will be
|
(a) ( |
(b) ( |
(c) ( |
(d) ( |
An electron is moving with a speed of perpendicular to a uniform magnetic field of intensity B. Suddenly intensity of the magnetic field is reduced to B/2. The radius of the path becomes from the original value of r
|
(a) No change |
(b) Reduces to r / 2 |
(c) Increases to 2r |
(d) Stops moving |
A photon of wavelength 4400 Å is passing through vacuum. The effective mass and momentum of the photon are respectively
|
(a) 5 |
(b) 5 |
|
(c) Zero, 1.5 |
(d) 5 |
Angle of minimum deviation for a prism of refractive index 1.5 is equal to the angle of prism. The angle of prism is (cos 41° = 0.75)
|
(a) 62° |
(b) 41° |
(c) 82° |
(d) 31° |
The distance between the plates of a parallel plate condenser is 8mm and P.D. 120 volts. If a 6mm thick slab of dielectric constant 6 is introduced between its plates, then
|
(a) The charge on the condenser will be doubled |
|
(b) The charge on the condenser will be reduced to half |
|
(c) The P.D. across the condenser will be 320 volts |
|
(d) The P.D. across the condenser will be 45 volts |