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