Class 12 Electromagnetic Waves CBSE Questions & Answers

Class 12 · Electromagnetic Waves

This is Physics Class 12 Electromagnetic Waves CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
State the part of the electromagnetic spectrum to which 1057 MHz (frequency of radiation arising from two close energy levels in hydrogen; known as Lamb shift)..Belongs
  • A
    Microwave
  • B
    Visible
  • C
    Ultraviolet
  • D
    Radio (short wavelength end)
    Correct
2
Part of the electromagnetic spectrum to which 2.7 K [temperature associated with the isotropic radiation filling all space-thought to be a relic of the ‘big-bang’ origin of the Universe] belongs is
  • A
    Radio (short wavelength end
  • B
    Ultraviolet
  • C
    Microwave
    Correct
  • D
    gamma rays
3
Part of the electromagnetic spectrum to which 5890 \(\mathop A\limits^0 \) - 5896 \(\mathop A\limits^0 \) [double lines of sodium] belongs is
  • A
    Microwave
  • B
    Ultraviolet
  • C
    Visible (Yellow)
    Correct
  • D
    gamma rays
4
Part of the electromagnetic spectrum to which 14.4 keV [energy of a particular transition in \(^{{\rm{57}}}{\rm{Fe}}\)nucleus associated with a famous high resolution spectroscopic method (Mossbauer spectroscopy)] belongs is
  • A
    Ultraviolet
  • B
    gamma rays
  • C
    Microwave
  • D
    X-rays (or soft \(\gamma \) -rays) region
    Correct
5
Long distance radio broadcasts use short-wave bands because
  • A
    Stratosphere reflects waves in these bands.
  • B
    Troposphere reflects waves in these bands.
  • C
    Ionosphere reflects waves in these bands.
    Correct
  • D
    None of the above
6
It is necessary to use satellites for long distance TV transmission because
  • A
    Television signals are attenuated by ionosphere
  • B
    Satellites transmit the signals all over the earth
  • C
    Television signals are absorbed by ionosphere
  • D
    Television signals are not properly reflected by the ionosphere. Therefore, reflection is effected by satellites.
    Correct
7
Optical and radio telescopes are built on the ground, but X-ray Astronomy is possible only from satellites orbiting the earth because
  • A
    Satellites orbiting the earth make use of interstellar effects
  • B
    Atmosphere reflects X-rays horizontally so they don’t reach the earth
  • C
    Atmosphere absorbs X-rays, while visible and radio waves can penetrate it.
    Correct
  • D
    Atmosphere reflects X-rays away from earth
8
The small ozone layer on top of the stratosphere is crucial for human survival because
  • A
    It prevents water molecules from escaping into space
  • B
    layer on top of the stratosphere is crucial as it supplies oxygen to atmosphere
  • C
    It absorbs ultraviolet radiations from the sun and prevents it from reaching the earth’s surface and causing damage to life.
    Correct
  • D
    None of the above
9
If the earth did not have an atmosphere, would its average surface temperature be higher or lower than what it is now?
  • A
    None of the above
  • B
    Higher as earth has poor reflectivity
  • C
    Lower because the Greenhouse effect of the atmosphere would be absent.
    Correct
  • D
    Higher as the heating is better
10
Some scientists have predicted that a global nuclear war on the earth would be followed by a severe ‘nuclear winter’ with a devastating effect on life on earth. What might be the basis of this prediction?
  • A
    Nuclear reactions absorb atmospheric heat causing cooling
  • B
    None of the above
  • C
    The clouds produced by global nuclear war would perhaps cover substantial parts of the sky preventing solar light from reaching many parts of the globe
    Correct
  • D
    Nuclear reactions absorb visible light causing dark days/nights
11
Do EM waves need a medium to travel through?
  • A
    Yes
  • B
    ether is required
  • C
    No
    Correct
  • D
    None of the above
12
Electromagnetic radiation.
  • A
    is neither a wave nor a particle but pure energy
  • B
    has both a wave and particle nature
    Correct
  • C
    is only particles
  • D
    is pure waves
13
High intensities of UV light
  • A
    kills dangerous bacteria and therefore good.
  • B
    are hazardous to the eyes
    Correct
  • C
    are low in energy
  • D
    is useful to good health
14
Which of these methods is better to reduce effects of ultra violet light
  • A
    Plastic lens eyeglasses
  • B
    Full coverage eye protection
    Correct
  • C
    Polycarbonate lens glasses
  • D
    Untreated eyeglasses
15
When white light is split into its component colors by a prism
  • A
    None of the above
  • B
    All of the electromagnetic spectrum
  • C
    you are looking at a part of the electromagnetic spectrum
    Correct
  • D
    You are not looking at electromagnetic spectrum but at colored light.