# Physics class -12th Chapter-8 ELECTROMAGNETIC WAVES Most VVI Objective Question

Q.1. Which of the following is of electromagnetic wave character

(A) B – rays

(B) a – rays

(C) y – rays

(D) none of these

Ans :- (C)

Q.2. Which one of the following has maximum penetrating power

(A) X – rays

(B) cathode rays

(C) a – rays

(D) y – rays

Ans :- (D)

Q.3. the phase difference between electric and magnetic fields in an electromagnetic wave is

(A) 0

(B) r/2

(C) r

(D) 1

Ans :- (B)

Q.4. The direction of propagation of electromagnetic wave is

(A) parallel to B

(B) parallel to e

(C) parallel to B × e

(D) parallel to e × B

Ans :- (D)

Q.5. The value of maximum amplitude produced due to interference of Two Waves is given by

y₁ = 4 sin wt and y₂ = 3 cos ωwt

(A) 7

(B) 5

(C) 1

(D) 25

Ans :- (A)

Q.6. The phase difference Φ is related to Path difference Δx by

(A) λ/π Φ

(B) π/λ Φ

(C) λ/2π Φ

(D) 2π/λ Φ

Ans :- (C)

Q.7. The electromagnetic wave with frequencies greater than TV signals and less than infrared waves, are called

(A) microwaves

(B) x – rays

(C) y – rays

(D) none of these

Ans :- (A)

Q.8. Which of the following help us for recognition of precious stone ?

(A) Ultraviolet rays

(B) Infrared

(C) X – rays

(D) none

Ans :- (C)

Q.9. Electromagnetic waves are produced by

(A) an accelerated charge

(B) a charge at rest

(C) uncharged particles

(D) uniformly moving charge

Ans :- (A)

Q.10. Accelerated charges produce

(A) α – rays

(B) γ – rays

(C) β – rays

(D) electromagnetic wave

Ans :- (D)

Q.11. Electromagnetic wave in free space is

(A) longitudinal

(B) transverse

(C) progressive

(D) none of these

Ans :- (B)

Q.12. Which of the following component of the electromagnetic spectrum is used in operating radar ?

(A) microwave

(C) X – rays

(D) γ – rays

Ans :- (A)

Q.13. What is the cause of conduction current?

(A) changing the magnetic flux

(B) changing the electric flux

(C) flow of the charge under the action of potential difference

(D) none of these

Ans :- (C)

Q.14. Which of the following is not electromagnetic wave ?

(A) sound wave

(B) X – rays

(D) microwave

Ans :- (A)

Q.15. In alternating circuit, the displacement current can be increased by increasing

(A) frequency of alternating current

(B) the time

(C) both ‘A’ and ‘B’

(D) none of these

Ans :- (A)

Q.16. Which of the following is not electromagnetic waves in nature ?

(A) X – rays

(B) γ – rays

(C) infrared rays

(D) cathode rays

Ans :- (D)

Q.17. Name the electromagnetic radiation used for viewing objets through haze and fog .

(B) Microwave

(C) X – rays

(D) none of these

Ans :- (A)

Q.18. The wavelength of X – rays (or e.m. waves) is the order of

(A) angstron

(B) micron

(C) millimeter

(D) meter

Ans :- (A)

Q.19. 1 roentgen is the unit of

(A) X – ray energy

(B) X – ray wavelength

(C) X – ray amount

(D) none of these

Ans :- (C)

Q.20. The discovery of X – ray was made by

(A) lave

(B) comption

(C) roentgen

(D) Coolidge

Ans :- (C)

Q.21. Name the electromagnetic wave can cause damage to tissues of the cells of human body

(A) microwaves

(C) X – rays

(D) cathode rays

Ans :- (C)

Q.22. Name the electromagnetic Waves which are stopped by bones

(A) X – rays

(B) infrared rays

(C) cathode rays

(D) none of these

Ans :- (A)

Q.23. X – rays are produced by

(A) discharge tube

(B) cathode ray tube

(C) Coolidge tube

(D) none of these

Ans :- (C)

Q.24. X – rays are similar to

(A) α-rays

(B) β-rays

(C) γ-rays

(D) cathode rays

Ans :- (C)

Q.25. Electromagnetic waves are produce by

(A) a static change

(B) a moving charge

(C) an accelerated charge

(D) chargless particle

Ans :- (C)

Q.26. Indentify which of the following electromagnetic spectrum having minimum frequency

(A) γ-rays

(C) microwave

(D) X-rays

Ans :- (B)

Q.27. Name the part of electromagnetic spectrum is used to produce in nuclear reactions

(A) microwaves

(C) γ-rays

(D) X-rays

Ans :- (C)

Q.28. The electromagnetic waves do not transport

(A) energy

(B) momentum

(C) charge

(D) information

Ans :- (C)

Q.29. Electromagnetic waves are transverse in nature is evident by

(A) polarisation

(B) interference

(C) reflection

(D) diffraction

Ans :- (A)

Q.30. Infrared radiation are defected by

(A) spectrometre

(B) Pyrometre

(C) nano metre

(D) photometre

Ans :- (B)

Q.31. earth’s atmosphere is richest in

(A) uttra violet rays

(B) infrared

(C) X- rays

(D) microwave

Ans :- (B)

Q.32. According to Maxwell’s shypothesis, a changing electric field gives rise to

(A) an emf

(B) ELectric current

(D) magnetic field

Ans :- (D)

Q.33. In general, the wavelength of microwave is

(A) More than that of radiowaves

(B) Less than that of UV waves

(C) More than that of IR waves

(D) Less than that IR waves

Ans:- (C)

Q.34. Which of the following will defiect in electric field

(A) X- ray

(B) Y- rays

(C) Cathode rays

(D) UV rays

Ans :- (C)

Q.35. Which wavelength of the sun is used finally is electric energy

(B) Infrared wave

(C) Visible light

(D) Microwave

Ans :- (B)

Q.36. When a high ultraviolet photon enters in an electric field it will be

(A) accelerated

(B) retarded

(C) undefiected

(D) none of these

Ans :- (C)

Q.37. What is the cause of green house effect

(A) infrared rays

(B) Ultraviolet rays

(C) X- rays

Ans :- (A)

Q.38. Infrared radiation was discovered by

(A) willian wollastan

(B) Willian hershel

(C) Williem Roentgen

(D) Thomas Young

Ans :- (B)

Q.39. Which of the following is a natural source of y- rays

Ans :- (C)

Q.40. Force required to stop a photon is

(A) ΔP/U

(B) ΔU/P

(C) ΔU/C

(D)ΔP/C

Ans :- (D)