In This Post we are  providing Chapter-8 Electromagnetic Waves NCERT MCQ for Class 12 Physics which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MCQ ON ELECTROMAGNETIC WAVES

Question 1.
The dimensional formula of E⃗  is:
(a)[MLT-2A-1]
(b) [MLT-3A-1]
(c) [MLT-2A-2]
(d) None of these

Answer: (b) [MLT-3A-1]

Question 2.
The dimensional formula of is:
(a) [MLT-2A-1]
(b) [ML0T-2A-1]
(c) [ML0T-3A-1]
(d) None of these

Answer: (b) [ML0T-2A-1]

Question 3.
Which of the following has the dimensions of current?
(a) ε0 E⃗ .dt→
(b) µ0 E⃗ .dt→
(c) B⃗ .dl→µ0
(d) B⃗ .dl→ε0

Answer: (c) B⃗ .dl→µ0

Question 4.
Which of the following has the dimensions of charge?
(a) ε0E⃗ ds→
(b) µ0 E⃗ .ds→
(c) ε0µ0 E⃗ .ds→
(d) µ0ε0 E⃗ .ds→

Answer: (a) ε0E⃗ ds→

Question 5.
Maxwell’s equation involving ddt B⃗  is obtained-from:
(a) Ampere’s law
(b) Gauss’s law
(c) Faraday’s law
(d) Biot-Savart’s law

Answer: (c) Faraday’s law

Question 6.
The dimensions of E⃗ , dl→ are identical to that of:
(a) potential
(b) charge
(c) current
(d) None of these

Answer: (a) potential

Question 7.
Which of the following laws was modified by Maxwell by introducing the displacement current?
(a) Gauss’s law
(b) Ampere’s law
(c) Biot-Savart’s law
(d).None of these

Answer: (b) Ampere’s law

Question 8.
Choose the wave relevant to telecommunication :
(a) ultraviolet
(b) infrared
(c) microwave
(d) visible light

Answer: (c) microwave

Question 9.
Electromagnetic waves have a speed of
(a) 3 × 105 kms-1
(b)3 × 106 kms-1
(c) 3 × 107 kms-1
(d) 3 × 108 kms-1

Answer: (a) 3 × 105 kms-1

Question 10.
Which of the following EMW has highest wavelength?
(a) X-ray
(b) ultraviolet rays
(c) infrared rays
(d) microwaves

Answer: (c) infrared rays

Question 11.
Displacement current is due to:
(a) the flow of electrons
(b) the Varying electric field
(c) the ionization of atmosphere
(d) the flow of protons

Answer: (b) the Varying electric field

Question 12.
Displacement current is always :
(a) equal to conduction current
(b) less than conduction current
(c) greater than conduction current
(d) the sum of current due to flow of positive and negative ions

Answer: (a) equal to conduction current

Question 13.
EMW are produced by:
(a) charge in uniform motion only
(b) charge at rest only
(c) accelerated or decelerated charge only
(d) all of the above

Answer: (c) accelerated or decelerated charge only

Question 14.
Who first demonstrated the existence of em waves?
(a) Hertz
(b) Maxwell
(c) Ampere
(d) Faraday

Answer: (a) Hertz

Question 15.
If B⃗  is the magnetic field vector and E⃗  is the electric field vector in an em wave, then which of the following relations is correct? Here c is the speed of fight:
(a) c = EB
(b) c = BE
(c) c = BE
(d) c = 1EB

Answer: (a) c = EB

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