MCQs of Electromagnetic Waves

Electromagnetic Waves MCQs

MCQs of Electromagnetic Waves

Showing 81 to 90 out of 112 Questions

81.

The intensity of a plane electromagnetic wave with E₀ = 18 Vm^-1 is _____ Wm^-2 (C = 3 × 10⁸ ms^-1, ε₀ = 8.85 × 10^-12 C²N^-1m^-2)

(a)	4.03
(b)	0.860
(c)	0.430
(d)	8.60

82.

At room temperature, if the relative permitittivity of water be 80 and the velocity of light in water is 2.25 × 10⁸ ms^-1, then the relative permeability of water is _____ .

(a)	0.0022
(b)	0.222
(c)	0.0222
(d)	2.022

83.

What is the minimum length of antenna to have efficient emission of radiation of wavelength 80 m ?

(a)	80 m
(b)	40 m
(c)	20 m
(d)	10 m

84.

\vec{E}

is the electric field and

\vec{B}

is the magnetic field then the dimensions of

\frac{E}{B}

is _____ .

(a)	M⁰L¹T^-1
(b)	M⁰L^-1T¹
(c)	M¹L¹T^-1
(d)	M¹L⁰T^-1

85.

At a short distance from a point like source, a wave propagating from it in three dimensional homogeneous and isotropic medium, the shape of wave front is _____ .

(a)	Cylindrical
(b)	Plane
(c)	Circular
(d)	Spherical

86.

Write dimensional formula for the intensity of radiation _____ .

(a)	M¹L²T^-2
(b)	M¹L²T^-3
(c)	M¹L⁰T^-3
(d)	M¹L⁰T^-3

87.

In a electromagnetic wave, the peak value of electric field is 60 Vm^-1. What is the average energy density of magnetic field of the wave ? μ₀= 4π × 10^-7 N/A², c = 3 × 10⁸ ms^-1

(a)	2π × 10^-7 J/m³
(b)	4π × 10^-7 J/m³
(c)	$\frac{1}{2 π} \times 10^{- 7} J / m^{3}$
(d)	$\frac{1}{4 π} \times 10^{- 7} J / m^{3}$

88.

Which of the following property is considered for the use of electron in electron microscope ?

(a)	Wave nature
(b)	Negative charge
(c)	Spin
(d)	None of the above

89.

The frequency of X - rays, γ - rays and ultra violet rays are respectively p, q and r, then _____ .

(a)	p < q, q > r
(b)	p < q, q < r
(c)	p > q, q > r
(d)	p > q, q < r

90.

The electric field of an electromagnetic wave in a medium is represented by E_x = 0 ;

E_{y} = 2.5 \frac{N}{C} c o s [(2 π \times 10^{6} \frac{r a d}{m}) t - (2 π \times 10^{- 2} \frac{r a d}{s}) x]

The electromagnetic wave is _____ .

(a)	moving along the X - direction with frequency 10⁶ Hz and wavelength 100 m
(b)	moving along the X - direction with frequency 10⁶ Hz and wavelength 200 m
(c)	moving along the negative X - direction with frequency 10⁶ Hz and wavelength 100 m
(d)	moving along the negative Y - direction with frequency 2π × 10⁶ Hz and wavelength 100 m

Showing 81 to 90 out of 112 Questions