Wave Optics — Physics STD 12 Science — Question

The current density (number of free electrons per m³) in metallic conductor is of the order of:

Assertion  : The electron in the hydrogen atom passes from energy level n = 4 to the n = 1 level. The maximum and minimum number of photon that can be emitted are six and one respectively.

Reason      : The photons are emitted when electron make a transition from the higher energy state to the lower energy state.

(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.

Two identical magnetic dipoles of magnetic moments 1.0 A-m² each, placed at a separation of 2m with their axis perpendicular to each other. The resultant magnetic field at a point midway between the dipoles is

(a) 5

(b)

(c)

(d) None of these

Tungsten has work function 4.8 eV. We wish to use tungsten as photo-cathode with a 600 nm wavelength. What shall we do?

Use of eddy currents is done in the following except

(a)  Moving coil galvanometer	(b)  Electric brakes
(c)  Induction motor	(d)  Dynamo

The displacement of a particle in simple harmonic motion in one time period is:

1. A
2. 2A
3. 4A
4. zero.

Which crystal is used in the Davisson – Germer experiment?

The angular dispersion produced by a prism:

1. Increases if the average refractive index increases.
2. Increases if the average refractive index decreases.
3. Remains constant whether the average refractive index increases or decreases.
4. Has no relation with average refractive index.

The surface with a constant value of potential at all points on the surface is called as: