8. ELECTROMAGNETIC WAVES( Objective Question Answer 2022 )


1. The dimensional formula of E is :

(A) [MLT-2A-1]
(B) [MLT-3A-1]
(C) [MLT-2A-2]
(D) None of these

Answer ⇒ B

2. Which of the following has the dimensions of current ?

Which of the following has the dimensions of current

Answer ⇒ A

3. Which of the following has the dimensions of charge ?

Which of the following has the dimensions of charge

Answer ⇒ A

4. Maxwell’s equation involving Maxwell's equation involvingis obtained from :

(A) Ampere’s law
(B) Gauss’s law
(C) Faraday’s law
(D) Biot-Savart’s law

Answer ⇒ C

5. The dimensions of The dimensions of are identical to that of :

(A) potential
(B) charge
(C) current
(D) None of these

Answer ⇒ A

6. 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

7. Choose the wave relevant to telecommunication :

(A) ultraviolet
(B) infrared
(C) microwave
(D) visible light

Answer ⇒ C

8. Electromagnetic waves have a speed of –

(A) 3 x 105 km s-1
(B) 3 x 106 km s-1
(C) 3 x 107 km s-1
(D) 3 x 108 km s-1

Answer ⇒ A

9. Which of the following EMW has highest wavelength ?

(A) X-ray
(B) ultraviolet rays
(C) infrared rays
(D) microwaves

Answer ⇒ C

10. 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

11. 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

12. EMW are produced by :

(A) charge in uniform motion only
(B) at rest only
(C) accelerated or deccelerated charge only
(D) all of the above

Answer ⇒ C

13. Who first demonstrated the existence of em waves ?

(A) Hertz
(B) Maxwell
(C) Ampere
(D) Faraday

Answer ⇒ A

14. If B is the magnetic field vector and É is the electric field vector in an em wave, then which of the following relations is correct ? Here c is the speed of light :

If B is the magnetic field vector and

Answer ⇒ A

15. The dimensions of E/B are same as that of :

(A) charge
(B) current
(C) velocity
(D) acceleration

Answer ⇒ C

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

(A) Biot-Savart’s law
(B) Faraday’s law
(C) Modified Ampere’s law
(D) None of these

Answer ⇒ C

17. The existence of EMW was experimentally established by :

(A) Sir S.C. Bose
(B) Maxwell
(C) Marconi
(D) Hertz

Answer ⇒ A

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

(A) Wavelength is doubled and the frequency remains unchanged
(B) Wavelength is doubled and the frequency become half
(C) Wavelength is halved and the frequency remains unchanged
(D) Wavelength and frequency both remain unchanged

Answer ⇒ C

19. Frequency of a wave is 6 x 1015 Hz. The wave is :

(A) Radiowave
(B) Microwave
(C) X-ray
(D) Ultra violet

Answer ⇒ D

20. Choose the wrong statement ?

(A) Electromagnetic waves are transverse
(B) Electromagnetic waves travel with the speed of light in free space
(C) Electromagnetic waves are produced by accelerating charges
(D) Electromagnetic waves travel with the same speed in all media

Answer ⇒ D

21. If ue and um are the electric and magnetic field densities in an electromagnetic wave, then (c is the speed of light) :

(A) ue = um
(B) ue = cum
(C) ue = um/c
(D) None Of These

Answer ⇒ A

22. Solar radiation is :

(A) transverse EMW
(B) longitudinal EMW
(C) both (A) and (B)
(D) None of these

Answer ⇒ A

23. Ampere’s circuital law was modified by :

(A) Laplace
(B) Gauss
(C) Maxwell
(D) Hertz

Answer ⇒ C

24. Light year is the unit of :

(A) distance
(B) time
(C) energy
(D) intensity of light

Answer ⇒ A

25. Which of the following helps us for recognition of precious stone ?

(A) Ultraviolet rays
(B) Infrared
(C) X-ray
(D) None

Answer ⇒ C

26. Oscillating electric circuits produce :

(A) Gamma rays
(B) X-rays
(C) Visible light
(D) Radiowaves

Answer ⇒ D

27. The wavelength range of visible light is :

(A) 4 x 10-7 to 8 x 10-7 m
(B) 4 x 10-6 to 8 x 10-8 m
(C) 4 x 10-5 to 8 x 10-9 m
(D) None of these

Answer ⇒ A

28. Choose the wave relevant to telecommunication :

(A) ultraviolet
(B) microwave
(C) infrared
(D) visible light

Answer ⇒ B

29. The direction of electromagnetic waves is given by :

(A) E.B
(B) ExB
(C) E/B
(D) EB

Answer ⇒ B

30. Velocity of light is given by :

Velocity of light is given by

Answer ⇒ B

31. In the above question, what is the amplitude of the oscillating magnetic field ?

(A) 1.6 x 10-3 T
(B) 1.6 x 10-6 T
(C) 1.6 x 10-3 m
(D) 1.6 x 10-7 T

Answer ⇒ D

32. In the above question, the total energy density (SI units) of the electromagnetic field of the wave is :

(A) 10-7
(B) 10-8
(C) 10-9
(D) 108

Answer ⇒ B

33. The energy density is expressed in :

(A) kg m-3
(B) Jm-2
(C) Jm-3
(D) J

Answer ⇒ C

Class 12th physics objective question in English

S.NPhysics Objective English Medium
1. ELECTRIC CHARGES AND FIELDS
2.LECTROSTATIC POTENTIAL AND CAPACITANCE
3.CURRENT ELECTRICITY
4.MOVING CHARGES AND MAGNETISM
5.MAGNETISM AND MATTER
6.ELECTROMAGNETIC INDUCTION
7.ALTERNATING CURRENT
8.ELECTROMAGNETIC WAVES
9.RAY OPTICS AND OPTICAL INSTRUMENTS
10.WAVE OPTICS
11.DUAL NATURE OF MATTER AND RADIATION
12.ATOMS
13.NUCLEI
14.SEMI CONDUCTOR ELECTRONICS 
15.COMMUNICATION SYSTEMS

 

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