Students are advised to practice the NCERT MCQ Questions for Class 12 Physics Chapter 8 Electromagnetic Waves with Answers Pdf free download is available here. MCQ Questions for Class 12 Physics with Answers are prepared as per the Latest Exam Pattern. Students can solve these Electromagnetic Waves Class 12 MCQs Questions with Answers and assess their preparation level.
Electromagnetic Waves Class 12 MCQs Questions with Answers
Solving the Electromagnetic Waves Multiple Choice Questions of Class 12 Physics Chapter 8 MCQ can be of extreme help as you will be aware of all the concepts. These MCQ Questions on Electromagnetic Waves Class 12 with answers pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. Have a glance at the MCQ of Chapter 8 Physics Class 12 and cross-check your answers during preparation.
I. Choose the correct answer
Question 1.
If \(\vec {E}\) and \(\vec {B}\) represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of electromagnetic wave is along
(a) \(\vec {E}\)
(b) \(\vec {B}\)
(c) \(\vec {B}\) × \(\vec {E}\)
(d) \(\vec {E}\) × \(\vec {B}\)
Answer
Answer: (d) \(\vec {E}\) × \(\vec {B}\)
Question 2.
The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is
(a) c : 1
(b) c² : 1
(c) 1 : 1
(d) √c : 1
Answer
Answer: (c) 1 : 1
Question 3.
A charged particle oscillates about its mean equilibrium position with a frequency of 109 Hz. The electromagnetic waves produced will not
(a) have a frequency of 109 Hz.
(b) have a frequency of 2 × 109 Hz.
(c) have a wavelength of 0.3 m.
(d) fall in the region of radio waves.
Answer
Answer: (b) have a frequency of 2 × 109 Hz.
Question 4.
The source of electromagnetic waves can be a charge
(a) moving with a constant velocity.
(b) moving in a circular orbit.
(c) at rest.
(d) none of these.
Answer
Answer: (b) moving in a circular orbit.
Question 5.
A plane electromagnetic wave of frequency 25 MHz travels in free space along the x-direction. At a particular point in space and time, the electric vector is \(\vec {E}\) = 6.3 Vm-1\(\hat {j}\). Calculate \(\vec {B}\) at
this point.
(a) 2.1 × 10-8 T
(b) 1.2 × 10-8 T
(c) 1.9 × 10-8 T
(d) 0.21 × 10-8T
Answer
Answer: (a) 2.1 × 10-8 T
Question 6.
What physical quantity is the same for X-rays of wavelength 10-10 m, red light of wavelength 680 nm and radio waves of wavelength 500 m?
(a) Wavelength
(b) Frequency
(c) Speed
(d) None of these.
Answer
Answer: (c) Speed
Question 7.
In an electromagnetic wave in free space, the root mean square value of the electric field is Erms = 6 V m-1. The peak value of the magnetic field is:
(a) 2.83 × 10-8 T
(b) 0.70 × 10-8 T
(c) 4.23 × 10-8 T
(d) 1.41 × 10-8 T
Answer
Answer: (a) 2.83 × 10-8 T
Question 8.
Arrange the following electromagnetic radiations per quantum in the order of increasing energy:
(A) Blue light
(B) Yellow light
(C) X-ray
(D) Radio wave
(a) A, B, C, D
(b) C, A, B, D
(c) B, A, D, C
(d) D, B, A, C
Answer
Answer: (d) D, B, A, C
Question 9.
A radiation of energy ‘E’ falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (c = Velocity of light)
(a) 2E/c
(b) 2E/c²
(c) E/c²
(d) E/c
Answer
Answer: (a) 2E/c
Question 10.
Match List -I (Electromagnetic wave type) with List – II (Its association/application) and select the correct option from the choices given below the lists:
| List I | List II |
| (A) Infrared | (i) To treat muscular strain |
| (B) Radio waves | (ii) For broadcasting |
| (C) X-rays | (iii) To detect fracture in bones |
| (D) Ultraviolet rays | (iv) Absorbed by the ozone layer of the atmosphere |
(a) A-iii, B-ii, C-i, D-iv
(b) A-i, B-ii, C-iii, D-iv
(c) A-iv, B-iii, C-ii, D-i
(d) A-i, B-ii, C-iv, D-iii
Answer
Answer: (b) A-i, B-ii, C-iii, D-iv
II. Fill in the blanks
Question 1.
The conduction current is same as …………………. whether the source is ac or dc.
Answer
Answer: Displacement current
Question 2.
The current that flows inside a capacitor is ………………. current.
Answer
Answer: Displacement
Question 3.
An oscillating charge particle radiates ……………….
Answer
Answer: EM wave
Question 4.
EM waves are …………….. in nature.
Answer
Answer: Transverse
Question 5.
EM waves travel with a speed …………………
Answer
Answer: 3 × 108 m s-1
Question 6.
Human body radiates ………………… of EM spectrum.
Answer
Answer: IR radiation
Question 7.
EM waves transport both ………………… and ………………..
Answer
Answer: Energy, momentum
Question 8.
EM waves are produced by ………………… charsed particles.
Answer
Answer: Accelerated
Question 9.
In terms of permittivity (ε0) of free space and permeability (µ0) of free space the velocity of EM wave is ………………..
Answer
Answer: c = \(\frac { 1 }{\sqrt{µ_0ε_0}}\)
Question 10.
The ratio of velocities of light waves of wavelengths 400 nm and 800 nm in vacuum is ………………..
Answer
Answer: 1 : 1
Question 11.
For an EM wave the electric field along the X-axis is given by Ex = E0 sin (kz – ωt) then magnetic field is given by ……………….
Answer
Answer: By = B0 sin (kz – ωt)
Question 12.
The maximum value of electric field (E0) and maximum value of magnetic field (B0) in EM wave are related as ………………
Answer
Answer: c = E0/B0
Question 13.
The energy of EM wave is divided …………….. amongst the electric and the magnetic field.
Answer
Answer: Equally
Question 14.
Shorter the wavelength of an electromagnetic wave ………………….. energy it carries.
Answer
Answer: More
Question 15.
The orderly distribution of electromagnetic radiations according to their frequency or wavelength is termed as ……………….. spectrum.
Answer
Answer: Electromagnetic
Question 16.
………………. are used as a diagnostic tool.
Answer
Answer: X-rays
Question 17.
For Sterilisation ……………….. rays are used.
Answer
Answer: Ultraviolet
Question 18.
For looking through haze ………………… are used.
Answer
Answer: Infrared
Question 19.
………………. are used for cooking.
Answer
Answer: Microwaves
Question 20.
Waves used to transmit cellular telephone message are ………………..
Answer
Answer: Microwaves
Question 21.
To study structure of crystals ……………….. are used.
Answer
Answer: X-rays
Question 22.
Human eye can detect ……………….. part of electromagnetic spectrum.
Answer
Answer: visible
Question 23.
To treat cancer and tumour in radiography ………………… rays are used.
Answer
Answer: y-rays
Question 24.
During the propagation of an EM wave in a medium electrical energy density is ………………….. to magnetic energy density.
Answer
Answer: Equal
Question 25.
For an EM wave propagating along x-axis Emax = 30 Vm-1, the maximum value of magnetic field is ………………..
Answer
Answer: 10-7T
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