Semiconductor Electronics: Materials, Devices and Simple Circuits — Physics STD 12 Science — Question

In an amplitude modulated wave for audio frequency of 500 cycle/second, the appropriate carrier frequency will be

(a) 50 cycles/sec

(b) 100 cycles/sec

(c) 500 cycles/sec

(d) 50,000 cycles/sec

A conducting loop carrying a current I is placed in a uniform magnetic field pointing into the plane of the paper as shown. The loop will have a tendency to

(a) Contract	(b) Expand
(c) Move towards +ve x –axis	(d) Move towards –ve x-axis

If each of the resistance of the network shown in the figure is R, the equivalent resistance between A and B is

(a) 5 R

(b) 3 R

(c) R

(d) R/2

NPN transistor are preferred to PNP transistor because they have

(a) Low cost

(b) Low dissipation energy

(c) Capability of handing large power

(d) Electrons having high mobility than holes

A proton is accelerated through 50,000 V. will increase Its energy by

(a) 5000 eV

(b) 8 J

(c) 5000 J

(d) 50,000 J

Unpolarized light of intensity 32Wm^–2 passes through three polarizers such that transmission axes of the first and second polarizer makes and angle 30° with each other and the transmission axis of the last polarizer is crossed with that of the first. The intensity of final emerging light will be

(a) 32 Wm–2

(b) 3 Wm–2

(c) 8 Wm–2

(d) 4 Wm–2

When the particle and its anti-particle unite, the result is:

A nucleus with mass number 220 initially at rest emits an a-particle. If the Q value of the reaction is 5.5 MeV, calculate the kinetic energy of the a-particle

(a) 4.4 MeV

(b) 5.4 MeV

(c) 5.6 MeV

(d) 6.5 MeV

The refractive index of a certain glass is 1.5 for light whose wavelength in vacuum is 6000 Å. The wavelength of this light when it passes through glass is

(a) 4000 Å

(b) 6000 Å

(c) 9000 Å

(d) 15000 Å

The chromatic Aberration in lenses becomes due to

(a) Disimilarity of main axis of rays

(b) Disimilarity of radii of curvature

(c) Variation of focal length of lenses with wavelength

(d) None of these