R4RIN – MCQs, Mock Tests | NCERT Class 12 MCQ Questions for Class 12 Physics Chapter 8 Electromagnetic Waves

The dimensional formula of E⃗ is:

1. [MLT-2A-1]
2. [MLT-3A-1]
3. [MLT-2A-2]
4. None of the above

✅ Correct Answer: 2

The dimensional formula of is

1. [MLT-2A-1]
2. [ML0T-2A-1]
3. [ML0T-3A-1]
4. None of the above

✅ Correct Answer: 2

Which of the following laws was modified by Maxwell by introducing the displacement current?

1. Gauss’s law
2. Ampere’s law
3. Biot-Savart’s law
4. None of the above

✅ Correct Answer: 2

Choose the wave relevant to telecommunication :

1. ultraviolet
2. infrared
3. microwave
4. visible light

✅ Correct Answer: 3

Electromagnetic waves have a speed of

1. (a) 3 × 105 kms-1
2. 3 × 106 kms-1
3. 3 × 107 kms-1
4. 3 × 108 kms-1

✅ Correct Answer: 1

Which of the following EMW has highest wavelength?

1. X-ray
2. ultraviolet rays
3. infrared rays
4. microwaves

✅ Correct Answer: 3

Displacement current is due to:

1. the flow of electrons
2. the Varying electric field
3. the ionization of atmosphere
4. the flow of protons

✅ Correct Answer: 2

Displacement current is always :

1. equal to conduction current
2. less than conduction current
3. greater than conduction current
4. the sum of current due to flow of positive and negative ions

✅ Correct Answer: 1

EMW are produced by:

1. charge in uniform motion only
2. charge at rest only
3. accelerated or decelerated charge only
4. All the above

✅ Correct Answer: 3

Who first demonstrated the existence of em waves?

1. Hertz
2. Maxwell
3. Ampere
4. Faraday

✅ Correct Answer: 1

The dimensions of E/Bare same as that of:

1. charge
2. current
3. velocity
4. acceleration

✅ Correct Answer: 3

Name the law which states that a varying electric field produces a magnetic field:

1. Biot-Savart’s law
2. Faraday’s law
3. Modified Ampere’s law
4. None of the above

✅ Correct Answer: 3

The existence of EMW was experimentally established by :

1. Sir S. C. Bose
2. Maxwell
3. Marconi
4. Hertz

✅ Correct Answer: 1

An EMW of v = 3 MHz passes from vacuum into dielectric medium with permittivity Er = 4, then:

1. Wavelength is doubled and the frequency remains unchanged
2. Wavelength is doubled and the frequency become half
3. Wavelength is halved and the frequency remains unchanged
4. Wavelength and frequency both remain unchanged

✅ Correct Answer: 3

Frequency of a wave is 6 × 1015. Hz. The wave is :

1. Radiowave
2. Microwave
3. X-ray
4. Ultra violet

✅ Correct Answer: 4

Choose the wrong statement?

1. Electromagnetic waves are transverse
2. Electromagnetic waves travel with the speed of light in free space
3. Electromagnetic waves are produced by accelerating charges
4. Electromagnetic waves travel with the same speed in all media

✅ Correct Answer: 4

Solar radiation is :

1. transverse EMW
2. longitudinal EMW
3. Both of the above
4. None of the above

✅ Correct Answer: 1

Ampere’s circuital law was modified by:

1. Laplace
2. Gauss
3. Maxwell
4. Hertz

✅ Correct Answer: 3

Light Year is the unit of:

1. distance
2. time
3. energy
4. intensity of light

✅ Correct Answer: 1