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

When Silicon is dopped with Boron as an impurity the resulting substance is :

Whenever current is changed in a coil, an induced e.m.f. is produced in the same coil, This property of the coil is due to.

If a conductor has a potential V ≠ 0 and there are no charges anywhere else outside, then:

A stream of electrons is projected horizontally to the right. A straight conductor carrying a current is supported parallel to electron stream and above it. If the current in the conductor is from left to right then what will be the effect on electron stream 

(a) The electron stream will be pulled upward

(b) The electron stream will be pulled downward

(c) The electron stream will be retarted

(d) The electron beam will be speeded up towards the right

Light of frequency n is incident on a substance of threshold frequency n₀(n₀ < n). The energy of the emitted photo-electron will be

(a)

(b) h/v

(c)

(d)

A long straight wire of circular cross section of radius'a carries a steady current 1. The current is uniformly distributed across its cross section. The ratio of magnitudes of the magnetic field at a point a/2 above the surface of wire to that of a point a 2 below its surface is

A uniform wire of resistance R is uniformly compressed along its length, until its radius becomes n times the original radius.  Now resistance of the wire becomes

(a)

(b)

(c)

(d) nR

A heating coil is labelled 100 W, 220 V. The coil is cut in half and the two pieces are joined in parallel to the same source. The energy now liberated per second is

(a) 200 J

(b) 400 J

(c) 25 J

(d) 50 J