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Physics NEET MCQ
Electromagnetic Wave And Communication Mcq
Quiz 3
Solution
Q.1.
The theory of electromagnetic waves predicted by Maxwell in 1888 was confirmed experimently first be
20%
a) Maxwell
60%
b) Hertz
20%
c)Marconi
0%
d)J.C.Bose
Q.2.
X-ray are produced by jumping of
20%
a) electrons from lower to higher energy orbit of atom
80%
b) electrons from higher to lower energy orbit of atom
0%
c)protons from lower to higher energy orbit of nucleus
0%
d)proton from higherr to lower energy orbit of nucleus
Q.3.
A radiowave has a maximum magnetic field induction of 10-4 T on arrival at a receving antenna. The maximum electric field intenisty of such wave is
0%
a) zero
20%
b) 3 ×104 V/m
60%
c) 5.8 × 10-9 V/m
20%
d) 3.3 × 10-13 V/m
Q.4.
The earth is surrounded by atmosphere up to a height of about
0%
a)200 km
60%
b) 400 km
40%
c)500 km
0%
d)600 km
Q.5.
Displacement current flows
20%
a) in between capacitor plates and wires of circuit
40%
b) in between capacitor plates only
20%
c)in resistance only
20%
d)depends on e.m.f of cell and value of R
Q.6.
Which of the following type of radiations are radiated by an oscillating electric charge
0%
a) electric
20%
b) magnetic
20%
c)thermoelectric
60%
d)electromagentic
Q.7.
The small ozone layer on top of the atmosphere is crucial for human survival because it
0%
a) has ions
20%
b) reflects raddio signals
60%
c) reflects UV rays
20%
d) reflects IR rays
Q.8.
In electromagnetic wave, the average energy density is associated to
0%
a)electric field only
20%
b) magnetic field only
80%
c)equally with electric and magnetic field
0%
d)average energy density is zzzero
Q.9.
In an electromagentic wave, the average energy density associated with magnetic field is
0%
a) LIo2 /2
20%
b) B2/ 2µo
60%
c)µoB2 / 2
20%
d)µo / 2B2
Q.10.
If E is an electric field and B is the magnetic induction, then the energy flow per unit area per unit time in an electromagnetic field is given by
40%
a) E × B
0%
b) E . B
20%
c)E2 + B2
40%
d)E/B
Q.11.
In an electromagnetic wave, the direction of the magnetic induction B is
40%
a) Parallel to the lectric field E
20%
b) Perpendicular to the lectic field E
40%
c) antiparallel to the polynting vector S
0%
d) radom
Q.12.
In a plane electromagentic wave propogating in space has an electric field of amlitude 9×103 V/m, then the amplitude of magnetic field is
0%
a)2.7 × 1012 T
20%
b) 9.0 × 10-3 T
40%
c)3.0 × 10-4 T
40%
d)3.0 × 10-5 T
Q.13.
A free electron is placed in the path of a plane electromagnetic wave, it will start moving along
0%
a) centre of earthh
0%
b) equator of earth
60%
c)magnetic field
40%
d)electric field
Q.14.
In an electromagnetic wave the average energy density associated with electric field is
0%
a) CV2 /2
40%
b) εo2 / 2E
0%
c)Q2/ 2C
60%
d)εoE2 / 2
Q.15.
Ozone blocks the radiations of wave length
20%
a) less than 3 × 10-7 m
20%
b) equal to 3 × 10-7 m
40%
c) more than 3 × 10-7 m
20%
d) all of these
Q.16.
The temperature variation in the region of stratosphere lies from
20%
a)290 K to 220 K
40%
b) 220 K to 280 K
20%
c)280 K to 180 K
20%
d)180 K to 700 K
Q.17.
Long distance radio broadcasts use short wave band because
20%
a) they have short wavelength
0%
b) they scatter less
60%
c)they are reflected by ionosphere
20%
d)they have more energy to propogate
Q.18.
The frequency from 3 to 30 MHz is known as
0%
a) audio band
20%
b) medium frequency band
60%
c)high frequency band
20%
d)very high frequecy band
Q.19.
The temperature variation in the region of stratosphere lies from
20%
a) 290 K to 220 K
60%
b) 220 K to 280 K
20%
c) 280 K to 180 K
0%
d) 180 K to 700 K
Q.20.
The electromagnetic waves
0%
a)travel with the speed of sound
0%
b) travel with the same speed in all medium
80%
c)travel in free space with the speed of light
20%
d)do not travel through medium
Q.21.
Which of the following electromagnetic waves have the longest wavelength
0%
a) heat waves
20%
b) light waves
40%
c)radio waves
40%
d)microwaves
Q.22.
Which of the following is of shortest wave length
0%
a) X-rays
60%
b) γ-rays
40%
c)microwaves
0%
d)radiowaves
Q.23.
The displacement current flows in a dielectric of capacitor, when potential difference across its plates
20%
c) becomes zero
40%
a) is increasing/ decreasing with tine
0%
b) is decreasing with times only
40%
d) becomes infinite
Q.24.
The nature of electric field in the region between the two plates of capacitor, while charging is
0%
a)always constant
20%
b) varying
60%
c)depends on value of C and R
20%
d)depends on e.m.f of battery
Q.25.
An electric field E and magnetic field B exists in a region. If these field are not perpendicular to each other, then the electromagnetic wave
20%
a) will not pass through the region
0%
b) will pass through region
80%
c)may pass through the region
0%
d)nothing is definite
Q.26.
The wavelength of ultraviolet rays is of the order of
0%
a) 10-3 m
20%
b) 10-6 m
0%
c)10-8 m
80%
d)between 'b' and 'c'
Q.27.
The energy of X-ray photon is 3.3 ×10-16 J its frequency is
20%
a) 2 × 1019 Hz
0%
b) 5 × 1018 Hz
60%
c) 5 × 1017 Hz
20%
d) 5 × 1016 Hz
Q.28.
The penitration power of X-ray increases with the increase in its
0%
a)velocity
40%
b) intensity
40%
c)frequency
20%
d)wave length
Q.29.
The voltage applied across an X-ray tube is nearly equal to
0%
a) 10 V
20%
b) 100 V
20%
c)1000 V
60%
d)10,000 V
Q.30.
The speed of electromagnetic wave is same for
0%
a) odd frequencies
60%
b) all frequencies
40%
c)all intensities
0%
d)even frequencies
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