Atoms — Physics STD 12 Science — Question

For harder X-rays:

1. The wavelength is higher.
2. The intensity is higher.
3. The frequency is higher.
4. The photon energy is higher.

In case of linearly polarized light, the magnitude of the electric field vector :

A radio transmitter operates at a frequency of 880 kHz and a power of 10 kW. The number of photons emitted per second are

(a) 1.72

(b) 1327

(c) 13.27

(d) 0.075

If the shift of wavelength of light emitted by a star is towards violet, then this shows that star is

(a) Stationary	(b) Moving towards earth
(c) Moving away from earth	(d) Information is incomplete

Assertion :   Electric conduction in gases is possible at normal pressure.

Reason     : The electric conduction in gases depends only upon the potential difference between the electrodes.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

Kirchhoff's second law in any closed circuit represents:

In the given figure, when key k is closed, then direction of induced current in the coil B IS:

What is produced by induction coil ?

Which of the following is / are true about the principle of Van de Graaff generator?

A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be

(a) Halved

(b) The same

(c) Doubled

(d) Quadrupled