Electromagnetic Waves — Physics STD 12 Science — Question

When the key K is pressed at time  t = 0, which of the following statements about the current I in the resistor AB of the given circuit is true

(a) I = 2 mA  at all t

(b) I oscillates between 1 mA and 2mA

(c) I = 1 mA at all t

(d) At t = 0 , I = 2 mA and with time it goes to 1 mA

Voltameter measures :

Characteristic of electromagnetic wave is shown by:

A rectangular loop carrying a current i is situated near a long straight wire such that the wire is parallel to the one of the sides of the loop and is in the plane of the loop. If a steady current I is established in wire as shown in figure, the loop will

(a) Rotate about an axis parallel to the wire

(b) Move away from the wire or towards right

(c) Move towards the wire

(d) Remain stationary

If the critical angle for total internal reflection from a medium to vacuum is 30°, the velocity of light in the medium is

(a) 3   m/s

(b) 1.5  m/s

(c) 6  m/s

(d)  m/s

Consider the following two statements regarding a linearly polarised, plane electromagnetic wave:

1. The electric field and the magnetic field have equal average values.
2. The electric energy and the magnetic energy have equal average values.

1. Both A and B are true.
2. A is false but B is true.
3. B is false but A is true
4. Both A and B are false.

_92​U²³⁸ absorbs a neutron. The product emits an electron. This product further emits an electron. The result is

Wave front formed by the collimator of a spectrometer:

An arrangement which consists of two conductors separated by a dielectric medium is called:

When the current change from + 2A to – 2A in 0.05 second, an e.m.f. of 8 V is induced in a coil. The coefficient of self-induction of the coil is

(a) 0.1 H

(b) 0.2 H

(c) 0.4 H

(d) 0.8 H