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CBSE Questions for Class 12 Medical Physics Electromagnetic Waves Quiz 9 - MCQExams.com

Which of the following represents an infra-red wavelength?
  • 104cm
  • 105cm
  • 106cm
  • 107cm
What is the wavelength range of visible light?
  • 4×107m to 8×107m
  • 4×109m to 8×109m
  • 4×105m to 8×105m
  • 4×106m to 8×106m
Electromagnetic wave of intensity 1400 W/m2 falls on metal surface on area 1.5 m2 is completely absorbed by it. Find out force exerted by beam.
  • 14×105N
  • 14×106N
  • 7×105N
  • 7×106N
At a particular instant, the current in the circuit given below is i. The displacement current between the plates of the capacitor shown below is
1114542_d59e19c9f7514a5ab6059c33c3ab43a6.png
  • Zero
  • i
  • i2
  • i4
The magnetic field in a plane electromagnetic wave is given by =2×107sin(0.5×103x+1.5×1011t). This electromagnetic wave is
  • Visible light
  • Infrared
  • Microwave
  • Radiowave
What is the wavelength of the wave whose frequency is 1012Hz
  • 0.3
  • 0.4
  • 0.5
  • 0.6
What is the type of invisible radiation from space that can be detected from Earth's surface?
  • Gamma rays
  • X-rays
  • Infrared radiation
  • Radio waves
A parallel plate condenser of capacity 1nF is connected to a battery of emf 2v though a resistance of 1MΩ. The displacement current after 103 sec is:
  • 0.37 μ A
  • 0.74 μ A
  • 1.48 μ A
  • 0.175 μ A
Mark the correct option in impure spectrum :
  • Order of colours is reverse
  • Order of colours is irregular
  • colours are overlapped
  • no colours is present
A parallel plate condenser has circular plates, each of radius 5cm. It is being charged so that electric field in the gap between its plates rises steadily at the rate of 1012V/ms.  What is the displacement current? 
  • 0.07A
  • 1.39A
  • 13.9A
  • 139A
An electromagnetic wave travels along z-axis. which of the following pairs of space and time varying fields would generate such a wave.
  • EX,BY
  • EY,BX
  • EZ,BX
  • EY,BZ
An ultrasound equipment work at frequency:
  •  Higher than 20,000Hz
  •  Higher than 10,000Hz
  •  Lower than 4420,000 Hz $$
  •  Lower than 10,000H2
A metal block is exposed to beams of X-ray of different wavelength. X-rays of which wavelength penetrate most?
  • 2oA
  • 4oA
  • 6oA
  • 8oA
If electric field in a non-magnetic medium for EM wave is given by E=100sin(108t+2z)ˆj then H is.
  • 50πsin(108t+2z)ˆi
  • 56πsin(108t+2z)ˆi
  • 20sin(108t+2z)ˆi
  • 25πsin(108t+2z)ˆj
Pick out the statement which is not true

  • IR radiatins are used for long distance photogtaphy
  • IR radiatins arise due to inner electon transitions in atoms
  • IR radiations are detected by using a bolometer
  • Sun is the natural source of IR radiation
Select the correct statement from the following
  • Electromagnetic waves cannot travel in vaccum
  • Electromagnetic waves are longitudinal waves
  • Electromagnetic waves are produced by charges moving with uniform velocity.
  • Electromagnetic waves carry both energy and momentum as they propagate through space.
If P represents radiation pressure, c represents speed of lights and l represents radiation energy striking a unit area per second, then non -zero integers x,y and z such that Pxlycz is dimensionless are
  • x=0,y=0,z=0
  • x=1,y=1,z=1
  • x=1,y=1,z=1
  • x=1,y=1,z=1
The longitudinal waves having frequency above 20 kHz are called
  • Infrasonic waves
  • Audible waves
  • Ultrasonic waves
  • Shock waves
The displacement current flows in a dielectric of a capacitor when the potential difference across its plates:
  • Has assumed constant value
  • Is decreasing with time
  • Is increasing with position
  • is zero
Which of the following have zero average value in a plane electromagnetic wave?
(i) Magnetic field
(ii) Electric field
(iii) Electric energy
(iv) Magnetic energy.
  • (i) and (ii)
  • (i) and (iv)
  • (ii) and (iii)
  • (iii) and (iv)
The infra-red spectrum lies between:
  • radio wave and micro-wave region
  • the micro-wave and visible region
  • the visible and ultra violet region
  • the ultra violet and the X-ray region
In Maxwell's velocity distribution curve area under the graph 
  • Increases when temperature is increased
  • Deccreases when temperature is increased
  • Remains same at all temperature
  • Depends on the pressure of the gas
Frequency ranges for micro waves are :
  • 3×109to3×104Hz
  • 3×1013to3×109Hz
  • 3×1014to3×109Hz
  • 3×1011to3×109Hz
Which of the following has maximum energy ?
  • radio waves
  • X rays
  • light waves
  • micro waves
X - ray beam can be deflected by 
  • Magnetic field
  • Electric field
  • Both (a) & (b)
  • None of these
The displacement current was named as current because
  • It is similar conduction current
  • It produced a magnetic field
  • It is a time varying field
  • It is current due to uniformly moving charge
Which one of the following is the primary effect of UV radiation caused due to depletion of ozone layer?
  • Heart attack
  • Skin cancer
  • High fever
  • All of these
  • None of these
An object is placed at some distance from a radio station. If the interval between transmission and reception of pulses is 2.66×102 sec, then the distance is?
  • 4000 km
  • 2000 km
  • 3000 km
  • 2500 km
The wavelength of a radio wave of frequency of 1 MHz is?
  • 400 m
  • 300 m
  • 350 m
  • 200 m
Assertion :- Microwave communication is preferred over optical communication. 
Reason :- Microwaves provide large number of channels and band width compared to optical signals. 
  • Both assertion and reason are true and the reason is correct explanation of assertion.

  • Both assertion and reason are true and the reason is not the correct explanation of assertion.

  • Assertion is true but reason is false.
  •  Both assertion and reason are false.
When ultraviolet rays incident on metal plate then photoelectric effect does not occure, it occursby incidence of
  • Infrared rays
  • X-rays
  • Radio wave
  • Green house effect
For an electromagnetic radiation,
  • only momentum is quantised
  • only energy is quantised
  • both energy and momentum are
    quantised
  • neither of them is quantised
Which one among the following waves are waves of heat energy?
  • Radiowaves
  • Infrared waves
  • Ultraviolet waves
  • Microwaves
Electromagnetic waves are :
  • Transverse waves
  • Longitudinal waves
  • Neither longitudinal nor transverse
  • Stationary waves
The radio waves of frequency 30 MHz to 300 MHz belong to:
  • high frequency band
  • very high frequency band
  • ultra high frequency band
  • super high frequency band.
A parallel plate capacitor of plate separation 2 mm is connected in an electric circuit having source voltageWhat is the value of the displacement current for 106 s, if plate area is 60 cm2
  • 1.062×102 A
  • 2.062×102 A
  • 3.062×102 A
  • 5.062×102 A
Which wavelength of harmful UV-radiations is prevented by ozone layer in entering the Earth atmosphere?
  • 210300nm
  • 200310nm
  • 120210nm
  • 400700nm
Which one of the following is not a electromagnetic waves?
  • X - rays
  • Gamma rays
  • cathode rays
  • Infrared rays
If the source of power 4kwW produces 1020 photons/second, the radiation belongs to the part of a spectrum called
  • X rays
  • Ultraviolet rays
  • Microwaves
  • Gamma rays
If a source of power 4 kW produces 1020 photons/second, the radiation belongs to a part of the spectrum called:-
  • γ-rays
  • X-rays
  • Ultraviolet rays
  • Microwave

The frequency of the electromagnetic wave, which best suited to observe a particle of the size 3×106m is of the order of:

  • 1014Hz
  • 1015Hz
  • 2×1013Hz
  • 3×1015Hz
Electro magnetic waves are transverse in nature as is evident by
  • polarization
  • interference
  • reflection
  • deffraction
The following can be arranged in decreasing order of wave number
A. AM radio
B. TV and FM radio
C. Microwave
D. Short radio wave
  • A > B > D > C
  • C > D > B > A
  • A > B > C > D
  • D > C > B > A
M and N are two electromagnetic waves.
The ratio wavelengthofMwavelengthofN=105. What could M and N be?

MN
AMicrowavesVisible light
BMicrowavesγ-rays
Cγ-raysMicrowaves
DVisible lightMicrowaves

  • A
  • B
  • C
  • D
If E=E0cos(kz)cos(ωt)ˆi then B for electromagnetic wave is:
  • B=E0Cˆk
  • B=E0Csin(kz)sin(ωt)ˆi
  • B=E0Csin(kz)cos(ωt)ˆj
  • B=E0Ccos(kz)sin(ωt)ˆj
The maximum kinetic energy of electron if wavelength of incident electromagnetic wave is 260nm and cut-off wavelength is 380nm given hc=1237nmeV is
  • 1.5eV
  • 6.4eV
  • 10eV
  • None of these
As its closest approach, the distance between Mars and the Earth is found to be 60 million km. When the planets are at the closest distance, how long would it take to send a radio message from a space probe of Mars of Earth?
  • 5 s
  • 200 s
  • 0.2 s
  • 20 s
A welder wears special glasses to protect his eyes mostly from the harmful effect of 
  • Very intense visible light
  • infrared radiation
  • ultraviolet rays
  • microwaves.
The diagram shows the principal regions of the electromagnetic spectrum, with some details labelled. The diagram is not to scale.
What is a typical order of magnitude of the wavelength of the radiation in region Q?

1641902_30c44dfcd7a84436b451b5080dcf808a.png
  • 107 m
  • 105 m
  • 102 m
  • 100 m
What is the main type of radiation given out by a campfire?
  • Infra-red
  • Microwave
  • Ultraviolet
  • X-ray
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