Q.1.
An electromagnetic wave going through vaccum is described by E=Eo sin(kx- ω t) then B=Bo sin(kx- ω t) then
-
57%
a) EoBo= ω k
-
29%
b) Eok = Bo ω
-
0%
c) Eo ω = Bok
-
14%
d) none of these
Q.2.
If the wavelength of light is 40000 A then the number of waves in 1mm length will be___
-
40%
a) 2.5
-
20%
b) 2500
-
0%
c) 250
-
40%
d) 25000
Q.3.
The SI unit of displacement current is_________
-
0%
a) coulomb
-
0%
b) henry
-
40%
c) ampere
-
60%
d) faraday
Q.4.
The electromagnetic waves do not transport_______
-
40%
a)energy
-
0%
b)charge
-
0%
c)momentum
-
60%
d)information
Q.5.
The frequency 1057MHz of radiation arising from two close energy levels inhydrogen belongs to_____
-
40%
a) radio waves
-
60%
b)infrared waves
-
0%
c)micro waves
-
0%
d)γ rays
Q.6.
Maxwell’s modified form of Ampere’s circuital law is____
-
40%
a)
-
60%
b)
-
0%
c)
-
0%
d)
Q.7.
The wavelength of x rays is of the order of
-
20%
a) 10–3 m
-
60%
b) 10–5 m
-
20%
c) 10–10 m
-
0%
d) 10–12 m
Q.8.
A point source of electromagnetic radiation has an average output power of 800W.The maximum value of electric field at a distance of 4.0m from the source is
-
20%
a)64.7V/m
-
60%
b)57.8V/m
-
20%
c)56.72V/m
-
0%
d)54.77V/m
Explanation
Q.9.
A plane electromagnetic wave Ez=100cos(6 ×108t + 4x) V/m propagate in a medium of refractive index
-
20%
a) 1.5
-
40%
b) 2.0
-
20%
c)2.4
-
20%
d)4.0
Q.10.
A plane electromagnetic wave of wave intensity 10 wm-2 strikes a small mirror ofarea 20 cm2 , held perpendicular to the approaching wave. The radiation force onthe mirror will be
-
50%
a)6.6×10-11 N
-
25%
b)1.33×10-11 N
-
25%
c)1.33×10-10 N
-
0%
d)6.6×10-10 N
Q.11.
An observer is at 2m from an isotropic point source of light emitting 40w power.The rm.s value of electric due to the source at the position of the observeris_____
-
0%
a) 5.77 × 10-8 V/m
-
0%
b) 17.3 V/m
-
75%
c) 57.7 × 10-8
-
25%
d) 1.73
Q.12.
The instrument/ equipment which transform one form of energy into another form of energy is called a _______
-
25%
a)transponder
-
0%
b) transducer
-
50%
c)receiver
-
25%
d)transmitter
Q.13.
Which of the following are modulation techniques for digital communication?
-
25%
a) ASK
-
0%
b) FSK
-
50%
c)PSK
-
25%
d)All of them
Q.14.
What is the main function of transponder
-
25%
a) To amplify the signal
-
0%
b) To change its frequency
-
50%
c)Both (a) and (b)
-
25%
d)none of them
Q.15.
Electromagnetic waves used in medicine to destroy cancer cells
-
25%
a) radio waves
-
25%
b) infrared rays
-
25%
c) gamma rays
-
25%
d) ultraviolet rays
Q.16.
In electromagnetic spectrum, the visible light lie between
-
0%
a)radiowaves and microwaves
-
25%
b) ultraviolet rays and infrared rays
-
50%
c)ultraviolet rays and x rays
-
25%
d)infrared rays and microwaves
Q.17.
Which of the following statements is not true in case of electromagnetic waves?
-
0%
a)they are light waves
-
100%
b)they are transverse waves
-
0%
c)propagates through space
-
0%
d)they are longitudinal waves
Q.18.
In an electromagnetic wave in free space, the direction of electric field vector E is along y axis and magnetic field vector B is along z axis then which of the following is true
-
0%
a)(E × B) × E=1
-
0%
b)(E × B) × B=1
-
75%
c)(E × B) × B=0
-
25%
d)none of these
Q.19.
When a plane electromagnetic wave travels in vacuum, the average electric energydensity is given by (Eo is the amplitude of the electric field)
-
25%
a)
-
50%
b)
-
0%
c)
-
25%
d)
Q.20.
In a plane electromagnetic wave , the electric field oscillates sinusoidaly at a frequency of 2.0×1010Hz. if the peak value of electric field is 60V/m the average energy density (in Jm-3) of the magnetic field of the wave will be
-
0%
a)2π×10-7
-
75%
b) 10-7 / 2π
-
0%
c)4π×10-7
-
25%
d) 10-7 / 4π
Q.21.
If the earth were not having atmosphere, its temperature________.
-
0%
a)would have been low
-
25%
b)would have been high
-
25%
c)would hav remain constant
-
50%
d)none of these
Q.22.
_________ is responsible for the green house effect
-
25%
a) infrared rays
-
25%
b) ultraviolet rays
-
50%
c)x raya
-
0%
d)radiowaves
Q.23.
When an electromagnetic wave encounters a dielectric medium, the transmittedwave has
-
50%
a) same frequency but different amplitude
-
50%
b) same amplitude but different frequency
-
0%
c) same frequency and amplitude
-
0%
d) different frequency and amplitude
Q.24.
An electromagnetic wave
-
0%
a)can be deflected by electric field
-
25%
b)can be deflected by magnetic field
-
75%
c)can be deflected bye both electric and magnetic field
-
0%
d)none of these
Q.25.
The potential difference between the plates of a parallel plate capacitor is chargingat the rate of 106V/s . If the capacitance is 2µF . The displacement current inthe dielectric of the capacitor will be
-
25%
a)4A
-
0%
b)3A
-
50%
c)2A
-
25%
d)1A
Q.26.
What should be the minimum length of the antenna capable of emitting audio signal ofwave length λ ?
-
50%
a)λ/4
-
0%
b) λ/8
-
50%
c)λ/2
-
0%
d)λ
Q.27.
_________is used as a medium an space communication
-
0%
a) Two wire line
-
25%
b) Space
-
75%
c) Amplifier
-
0%
d) Optical fibre
Q.28.
The band width of Audio signal is
-
0%
a)20 HZ
-
50%
b)20 KHZ
-
25%
c)20 MHz
-
25%
d)20 GHz
Q.29.
ground waves are polarized at direction.
-
0%
a)vertically upward
-
0%
b)horizontal
-
25%
c)tangential direction to the surface of the earth
-
75%
d)in all four.
Q.30.
Intensity of electric field of ground waves is in of the distance travelled by it.
-
25%
a) Square
-
25%
b) inverse of root
-
25%
c)proportion
-
25%
d)inverse