Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Two important processes that occur during the formation of a p-n junction.

If the current is halved in a coil, then the energy stored is how much times the previous value

(a)

(b)

(c) 2

(d) 4

Two short magnets with their axes horizontal and perpendicular to the magnetic meridian are placed with their centres 40 cm east and 50 cm west of magnetic needle. If the needle remains undeflected, the ratio of their magnetic moments   is

(a) 4 : 5

(b) 16 : 25

(c) 64 : 125

(d) 2 :

Among the particles moving with the same velocity, the de Broglle wavelength will be maximum of :

Sky wave propagation is based on :

In a Wheatstone’s bridge all the four arms have equal resistance R.  If the resistance of the galvanometer arm is also R, the equivalent resistance of the combination as seen by the battery is

(a)

(b) R

(c) 2R

(d)

Four plates of equal area A are separated by equal distances d and are arranged as shown in the figure. The equivalent capacity is

(a)

(b)

(c)

(d)

Two light beams superimposed each other constructively this results in:

The explosion of hydrogen bomb is based on the principle of:

A uniform but time-varying magnetic field B(t) exists in a circular region of radius a and is directed into the plane of the paper, as shown. The magnitude of the induced electric field at point P at a distance r from the centre of the circular region

(a) Is zero

(b) Decreases as

(c) Increases as r

(d) Decreases as