Nuclei — Physics STD 12 Science — Question

In the depletion region of a pn junction, there is a shortage of:

When light propagates in vacuum there is an electric field and a magnetic field. These fields:

1. Are constant in time.
2. Have zero average value.
3. Are perpendicular to the direction of propagation of light.
4. Are mutually perpendicular.

Inside a hollow charged spherical conductor, the potential

(a) Is constant

(b) Varies directly as the distance from the centre

(c) Varies inversely as the distance from the centre

(d) Varies inversely as the square of the distance from the centre

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

 Identify the type of conductors whose V-I relationship is linear.

Molybdenum is used as a target element for production of X-rays because it is

(a) A heavy element and can easily absorb high velocity electrons

(b) A heavy element with a high melting point

(c) An element having high thermal conductivity

(d) Heavy and can easily deflect electrons

One Tesla is equal to

(a)

(b)

(c)

(d)

Assertion  :   The possibility of an electric bulb fusing is higher at the time of switching ON and OFF

Reason     : Inductive effects produce a surge at the time of switch ON and OFF

(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 field due to a magnet at a distance R from the centre of the magnet is proportional to

(a)

(b)

(c)

(d)

The equation of an alternating voltage is E = 220 E = 220.Then the impedance of the circuit is: