Nuclei — Physics STD 12 Science — Question

A photon of wavelength 6630 Å is incident on a totally reflecting surface. The momentum delivered by the photon is equal to

(a) 6.63 × 10–27 kg-m/sec

(b) 2 × 10–27 kg-m/sec

(c) 10–27 kg-m/sec

(d) None of these

Consider the situation of the previous problem. The directions of the magnetic field due to the dipole are opposite at:

Magnetic lines of force

(a) Always intersect

(b) Are always closed

(c) Tend to crowd far away from the poles of magnet

(d) Do not pass through vacuum

Choose the correct statement:

The direction of electric field created by a negative charge is ___________?

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.

A cell of emf 6 V and resistance 0.5 ohm is short circuited.  The current in the cell is

(a) 3 amp

(b) 12 amp

(c) 24 amp

(d) 6 amp

Assertion :   Intensity of X-rays can be controlled by adjusting the filament current and voltage.

Reason     : The intensity of X-rays does not depend on number of X-ray photons emitted per second from the target.

(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.

The thickness of the depletion region is of the order of ___________ of a micrometre.

Light is an electromagnetic wave. Its speed in vacuum is given by the expression

(a)

(b)

(c)

(d)