### Physics - Electromagnetic Waves

#### Question - 1

What is the progation velocity of an electromagnetic wave in a medium for which relative permittivity, ${ \epsilon }_{ r }$ = 3.1, and relative permeability, ${ \mu }_{ r }$ = 200 ?

• A 3.0 $\times$ 1010 ms-1
• B 1.20 $\times$ 107 ms-1
• C 3.60 $\times$ 107 ms-1
• D 1.5 $\times$ 108 ms-1

#### Question - 2

A broadcasting station transmits radio waves of wavelength 300 m. What is the inductance of an inductor that could be connected with a 2.40-$\mu$F capacitor to be in resonance with these waves?

• A 3.3 $\times$ 10-2 H
• B 3.3 $\times$ 10-8 H
• C 3.3 $\times$ 10-5 H
• D 1.04 $\times$ 10-8 H

#### Question - 3

A viberating electric charge radiates

• A electric waves
• B magnetic waves
• C both (a) and (b)
• D light waves

#### Question - 4

In an electromagnetic wave, light vector is

• A electric vector
• B magnetic vector
• C electromagnetic vector

#### Question - 5

For electomagnetic waves propagating along x-axis, the wave must have the components

• A (Ex, Hy)
• B (Ey, Ez)
• C (Ey, Hy)
• D (Hy, Ez)

#### Question - 6

Which is NOT a part of electromagnetic spectrum?

• A Beta rays
• B Gamma rays
• C Wireless waves
• D T. V. waves

#### Question - 7

Rate of change of displacement vector has the dimension of

• A charge per unit area
• B current
• C current per unit area
• D charge

#### Question - 8

Choose INCORRECT statement :

• A Optics is the branet of electromagnetism
• B The speed of electomagnetic waves depends only on electric and magnetic properties of the medium they travel in, and not on the amplitudes of field variations.
• C Displacement current is NOT a current in the real sense.
• D Without displacement current, the electromagnetic radiation would have been possible.

#### Question - 9

Choose INCORRECT statement :

• A A light wais charcterised by its electric vector $\overset { \rightarrow }{ E }$, although it has a magnetic vector $\overset { \rightarrow }{ H }$.
• B It is the electric field vector which is responsible for all optical phenomena.
• C Displacement current and conduction crrent in an electric circuit may not be continuous but their sum is always continuous.
• D Displacement current is due to rate of flow charge between plates of a capacitor.

#### Question - 10

A  T.V. transmission tower has a height of 200 m. By how much should the height be increased to double its covering range?

• A 400 m
• B 600 m
• C 800 m
• D 300 m