Moving Charges and Magnetism — Physics STD 12 Science — Question

Zener diode is used for:

When an electromagnetic wave enters an ionised layer of earth’s atmosphere present in ionosphere:

In an A.C. circuit, the capacitive reactance is defined as __________ .

The particle that possesses half integral spin is:

An antenna is a device

(a) That converts electromagnetic energy into radio frequency signal

(b) That converts radio frequency signal into electromagnetic energy

(c) That converts guided electromagnetic waves into free space electromagnetic waves and vice-versa

(d) None of these

In an inductor of inductance L = 100 mH, a current of I = 10A is flowing. The energy stored in the inductor is

(a) 5 J

(b) 10 J

(c) 100 J

(d) 1000 J

There are two equipotential surface as shown in figure. The distance between them is r. The charge of –q coulomb is taken from the surface A to B, the resultant work done will be

(a)

(b)

(c)

(d)

Assertion :   Reduction factor (K) of a tangent galvanometer helps in reducing deflection to current.

Reason     : Reduction factor increases with increase of current.

(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.

In an electron gun, the electrons are accelerated by the potential V.  If e is the charge and m is the mass of an electron, then the maximum velocity of these electrons will be

(a)

(b)

(c)

(d)