Electromagnetic Waves — Physics STD 12 Science — Question

Two infinitely long parallel wires having linear charge densities   and  respectively are placed at a distance of R metres. The force per unit length on either wire will be   )

(a)

(b)

(c)

(d)

The graph Shows the variation in magnetic flux ∅(t) with time through a coil. Which of the statements given below is not correct

(a) There is a change in the direction as well as magnitude of the induced emf between B and D

(b) The magnitude of the induced emf is maximum between B and C

(c)There is a change in the direction as well as magnitude of induced emf between A and C

(d) The induced emf is zero at B

For ferromagnetic material, the relative permeability (, versus magnetic intensity (H) has the following shape

(a)

(b)

(c)

(d)

A particle is fastened at the end of a string and is whirled in a vertical circle with the other end of the string being fixed. The motion of the particle is:

1. Periodic.
2. Oscillatory.
3. Simple harmonic.
4. Angular simple harmonic.

Consider the situation shown in figure. The wire AB is slid on the fixed rails with a constant velocity. If the wire AB is replaced by a semicircular wire, the magnitude of the induced current will: 

A NPN transistor conducts when

(a) Both collector and emitter are positive with respect to the base

(b) Collector is positive and emitter is negative with respect to the base

(c) Collector is positive and emitter is at same potential as the base

(d) Both collector and emitter are negative with respect to the base

ike magnetic force ______ each other.

The phenomena of total internal reflection is seen when angle of incidence is

(a) 90°	(b) Greater than critical angle
(c) Equal to critical angle	(d) 0°

An artificial radioactive decay series begins with unstable . The stable nuclide obtained after eight α - decays and five β- decays is

(a)

(b)

(c)

(d)

The frequency of A.C mains in India is.