Q.1
green-house effect is the heating up of earth's atmosphere due to ... [ CBSE-PMT 2002]
  • a) green plants
  • b) infra-red rays
  • c)X-rays
  • d)β-rays
Q.2
Pick out the longest wavelength from the following types of radiation... [ CBSE-PMT 1990]
  • a) blue light
  • b) gamma rays
  • c)X-rays
  • d)red light
Q.3
It is necessary to use satelite for long distance TV transmission because
  • a)T.V. signals has short wave length
  • b) TV signal has long wavelength
  • c)TV signal has light signals
  • d)TV signals are not reflected by ionosphere
Q.4
Which of the following waves have the maximum wavelength .. [ AFMC 2002]
  • a)Infrared rays
  • b) UV rays
  • c)Radio waves
  • d)X-rays
Q.5
Which scientist experimentally proved the existence of electromagnetic wave. [ AFMC 2004]
  • a) Sir J.C Bose
  • b) Maxwell
  • c)Marconi
  • d)Hertz
Q.6
The direction of propagation of electromagnetic waves is given by the direction of ..[ AFMC 2011]
  • a)Vector E
  • b) Vector B
  • c)Vector (E × B )
  • d)none of these
Q.7
If the magnetic field of a light wave oscillates parallel to y-axis and is given by By=Bmsin(kz-ωt), the direction of wave travel and the axis along which the electric vector oscillates is .. [ AIIMS 2011]
  • a) +ve y-axis, z-axis
  • b) -ve z-axis , x-axis
  • c) -ve x axis , y-axis
  • d) -ve x axis, z-axis
Q.8
A TV tower has height of 100m. How much population is covered by the TV broadcast if the average population density around the tower is 1000km-2> ( radius of earth=6.37× 106m) [ AFMC 2009]
  • a) 4 lakh
  • b) 4 billion
  • c) 40,000
  • d) 40 lakh
Q.9
Ozone layer in atmosphere is, useful, because it... [ AFMC 2007]
  • a) stops ultraviolet radiation
  • b) absorbs pollutant gases
  • c)stops green house effect
  • d)stops increase in temperature of atmosphere
Q.10
According to Maxwell's hypothesis, changing of electric filed give rise to.. [ AIIMS 1999]
  • a) magnetic filed
  • b) pressure gradient
  • c)charge
  • d)voltage
Q.11
In communication with the help of antenna if height is double then the range covered which was initially 'r' would become
  • a) (√2)r
  • b) 3r
  • c) 4r
  • d) 5r
Q.12
Communication on ground is through electromagnetic waves of wavelength [ AIIMS 2010]
  • a)larger than 600 m
  • b) between 200 and 600 m
  • c)between 1 and 5 m
  • d)between 10-3 and 0.1
Q.13
If the highest modulating frequency of the wave is 5kHz, the number of stations that can be accommodated in a 150kHz band width are .. [ AIIMS 2007]
  • a) 15
  • b) 10
  • c)5
  • d)none of these
Q.14
) If intensity of wave is 0.03W/m2, energy density of radiation is ... C=3×108 m/s
  • a) 106 J m-3
  • b) 10-6 J m-3
  • c)10-10 J m-3
  • d)1010 J m-3
Q.15
) If energy in form of electromagnetic waves being incident on the surface is U, momentum gained by the surface is ... ( Energy is completely absorbed by the surface)
  • a) p=U2 / C
  • b) p=U / C2
  • c) p=U/C
  • d) p=2U/ C
Q.16
The electromagnetic radiation is caused by.. [ CBSE-PMT 1999]
  • a) stationary charge
  • b) uniformly moving charges
  • c)accelerated charges
  • d)all of above
Q.17
The oscillating electric and magnetic field vectors of electromagnetic eave are oriented along.. [ CBSE-PMT 1994]
  • a)the same direction and in phase
  • b) the same direction but have a phase difference of 90°
  • c)mutually perpendicular directions and are in phase
  • d)mutually perpendicular directions but has a phase difference of 90°
Q.18
The electric and magnetic field of an electromagnetic wave are... [ CBSE-PMT 2007]
  • a) in opposite phase and perpendicular to each other
  • b) in opposite phase and parallel to each other
  • c)in phase and perpendicular to each other
  • d)in pahse and parallel to each other
Q.19
If E and B represent electric and magnetic field vectors of the electromagnetic waves, then the direction of propogation of the waves will be along.. [ CBSE-PMT 2002]
  • a) B × E
  • b) E
  • c) B
  • d) E×B
Q.20
Which of the following statement is false for the properties of electromagnetic waves? [ CBSE-pMT 2010]
  • a)Both electric and magnetic field vector attain the maxima and minimuma at the same place and same time
  • b) the energy in electromagnetic wave divided equally between electric and magnetic vectors
  • c)Both electric and magnetic vectors are parallel to each other and perpendicular to the direction of propagation
  • d)these wave do not require any material medium for propagation
Q.21
Which one of the following ray is not electromagnetic wave? [ CBSE-PMT2003]
  • a) heat rays
  • b) X-rays
  • c) γ-rays
  • d) β-rays
Q.22
) A gold leaf electroscope is charged and the leaves are observered to diverge by a certain amount. A beam of X-rays is allowed to fall upon the electroscope for short periode. The leaves would
  • a)collapse
  • b) melt
  • c)diverge more
  • d)remains at same divergence
Q.23
The density of air at the top of mesosphere in comparison to that of near the earth's surface is
  • a) 10-3
  • b) 10-5 times
  • c)103 times
  • d) 105 times
Q.24
The density of air the top of stratosphere in comparison to that of near the earth's surface is
  • a) 10-2 times
  • b) 10-5 times
  • c)102 times
  • d)103 times
Q.25
The shortest wavelength of X-ray emitted from an X-ray tube depends upon
  • a) nature of the gas in the tube
  • b) voltage applied to tube
  • c) current in the tube
  • d) nature of traget of the tube
Q.26
Whose experiemts mark the begining of the field of communication using electromagnetic waves
  • a)Maxwell
  • b) Hertz
  • c)Marconi
  • d)J.CBose
Q.27
Ground waves have a wavelength
  • a) less than 200 m
  • b) equal to 200 m
  • c)more than 200 m
  • d)all of these
Q.28
Radiowaves with frequencies higher than television signals are
  • a) ultrasonic waves
  • b) sound waves
  • c)infrasonic waves
  • d)microwaves
Q.29
The production of X-rays is a phenomenon for the conservation of
  • a) mass into potential energy
  • b) mass into heat
  • c) kinetic energy into radiant energy
  • d) charge
Q.30
Radiowaves do not penetrate in the region of
  • a)ionosphere
  • b) mesosphere
  • c)troposphere
  • d)statosphere
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