green-house effect is the heating up of earth's atmosphere due to ... [ CBSE-PMT 2002]
8%
a) green plants
92%
b) infra-red rays
0%
c)X-rays
0%
d)β-rays
Q.2.
Pick out the longest wavelength from the following types of radiation... [ CBSE-PMT 1990]
23%
a) blue light
15%
b) gamma rays
8%
c)X-rays
54%
d)red light
Q.3.
It is necessary to use satelite for long distance TV transmission because
13%
a)T.V. signals has short wave length
27%
b) TV signal has long wavelength
0%
c)TV signal has light signals
60%
d)TV signals are not reflected by ionosphere
Q.4.
Which of the following waves have the maximum wavelength .. [ AFMC 2002]
0%
a)Infrared rays
0%
b) UV rays
91%
c)Radio waves
9%
d)X-rays
Q.5.
Which scientist experimentally proved the existence of electromagnetic wave. [ AFMC 2004]
8%
a) Sir J.C Bose
58%
b) Maxwell
8%
c)Marconi
25%
d)Hertz
Q.6.
The direction of propagation of electromagnetic waves is given by the direction of ..[ AFMC 2011]
0%
a)Vector E
0%
b) Vector B
92%
c)Vector (E × B )
8%
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]
30%
a) +ve y-axis, z-axis
40%
b) -ve z-axis , x-axis
20%
c) -ve x axis , y-axis
10%
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]
11%
a) 4 lakh
33%
b) 4 billion
22%
c) 40,000
33%
d) 40 lakh
Q.9.
Ozone layer in atmosphere is, useful, because it... [ AFMC 2007]
70%
a) stops ultraviolet radiation
0%
b) absorbs pollutant gases
20%
c)stops green house effect
10%
d)stops increase in temperature of atmosphere
Q.10.
According to Maxwell's hypothesis, changing of electric filed give rise to.. [ AIIMS 1999]
90%
a) magnetic filed
0%
b) pressure gradient
0%
c)charge
10%
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
56%
a) (√2)r
0%
b) 3r
44%
c) 4r
0%
d) 5r
Q.12.
Communication on ground is through electromagnetic waves of wavelength [ AIIMS 2010]
11%
a)larger than 600 m
33%
b) between 200 and 600 m
11%
c)between 1 and 5 m
44%
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]
57%
a) 15
14%
b) 10
29%
c)5
0%
d)none of these
Q.14.
) If intensity of wave is 0.03W/m2, energy density of radiation is ... C=3×108 m/s
0%
a) 106 J m-3
9%
b) 10-6 J m-3
64%
c)10-10 J m-3
27%
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)
0%
a) p=U2 / C
25%
b) p=U / C2
62%
c) p=U/C
12%
d) p=2U/ C
Q.16.
The electromagnetic radiation is caused by.. [ CBSE-PMT 1999]
0%
a) stationary charge
12%
b) uniformly moving charges
62%
c)accelerated charges
25%
d)all of above
Q.17.
The oscillating electric and magnetic field vectors of electromagnetic eave are oriented along.. [ CBSE-PMT 1994]
0%
a)the same direction and in phase
10%
b) the same direction but have a phase difference of 90°
60%
c)mutually perpendicular directions and are in phase
30%
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]
12%
a) in opposite phase and perpendicular to each other
12%
b) in opposite phase and parallel to each other
62%
c)in phase and perpendicular to each other
12%
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]
25%
a) B × E
0%
b) E
0%
c) B
75%
d) E×B
Q.20.
Which of the following statement is false for the properties of electromagnetic waves? [ CBSE-pMT 2010]
14%
a)Both electric and magnetic field vector attain the maxima and minimuma at the same place and same time
14%
b) the energy in electromagnetic wave divided equally between electric and magnetic vectors
57%
c)Both electric and magnetic vectors are parallel to each other and perpendicular to the direction of propagation
14%
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]
50%
a) heat rays
17%
b) X-rays
0%
c) γ-rays
33%
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
50%
a)collapse
0%
b) melt
17%
c)diverge more
33%
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
0%
a) 10-3
40%
b) 10-5 times
60%
c)103 times
0%
d) 105 times
Q.24.
The density of air the top of stratosphere in comparison to that of near the earth's surface is
20%
a) 10-2 times
60%
b) 10-5 times
0%
c)102 times
20%
d)103 times
Q.25.
The shortest wavelength of X-ray emitted from an X-ray tube depends upon
33%
a) nature of the gas in the tube
33%
b) voltage applied to tube
17%
c) current in the tube
17%
d) nature of traget of the tube
Q.26.
Whose experiemts mark the begining of the field of communication using electromagnetic waves
17%
a)Maxwell
67%
b) Hertz
17%
c)Marconi
0%
d)J.CBose
Q.27.
Ground waves have a wavelength
0%
a) less than 200 m
0%
b) equal to 200 m
100%
c)more than 200 m
0%
d)all of these
Q.28.
Radiowaves with frequencies higher than television signals are
20%
a) ultrasonic waves
0%
b) sound waves
40%
c)infrasonic waves
40%
d)microwaves
Q.29.
The production of X-rays is a phenomenon for the conservation of
33%
a) mass into potential energy
0%
b) mass into heat
33%
c) kinetic energy into radiant energy
33%
d) charge
Q.30.
Radiowaves do not penetrate in the region of
67%
a)ionosphere
17%
b) mesosphere
0%
c)troposphere
17%
d)statosphere
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