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Class 12 Physics Chapter 8 Electromagnetic Waves Solved Question Answers

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Free download in PDF Class 12 Physics Chapter 8 Electromagnetic Waves Current Induction Multiple Choice Questions and Answers for Board, JEE, NEET, AIIMS, JIPMER, IIT-JEE, AIEE and other competitive exams. MCQ Questions for Class 12 Physics with Answers were prepared based on the latest exam pattern. These short solved questions or quizzes are provided by Gkseries. These will help the students for preparation of their examination./p>

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(1) Who first demonstrated the existence of em waves?
[A] Hertz
[B] Maxwell
[C] Ampere
[D] Faraday
Answer: Hertz
(2) 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: 3 × 105 kms-1

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(3) 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: Modified Ampere’s law
(4) The dimensions of
[A] potential
[B] charge
[C] current
[D] None of these
Answer: potential
(5) The dimensional formula of is:
[A] [MLT-2A-1]
[B] [ML0T-2A-1]
[C] [ML0T-3A-1]
[D] None of these
Answer: [ML0T-2A-1]
(6) Maxwell’s equation involving is obtained-from:
[A] Ampere’s law
[B] Gauss’s law
[C] Faraday’s law
[D] Biot-Savart’s law
Answer: Faraday’s law
(7) 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: Wavelength is halved and the frequency remains unchanged
(8) Solar radiation is :
[A] transverse EMW
[B] longitudinal EMW
[C] both (a) and (b)
[D] None of these
Answer: transverse EMW
(9) Light Year is the unit of:
[A] distance
[B] time
[C] energy
[D] intensity of light
Answer: distance
(10) Frequency of a wave is 6 × 1015. Hz. The wave is :
[A] Radiowave
[B] Microwave
[C] X-ray
[D] Ultra violet
Answer: Ultra violet
(11) If is the magnetic field vector and 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 = E/B
[B] c = B/E
[C] c = B/E
[D] c = 1/EB
Answer: c = E/B
(12) Which of the following has the dimensions of current?
[A]
[B]
[C]
[D]
Answer: C
(13) The ratio of the amplitude of the magnetic field to the amplitude of the electric field for electromagnetic wave propagation in a vacuum is equal to
[A] Unity
[B] Speed of light in vacuum
[C] Reciprocal of the speed of light in vacuum
[D] The ratio of magnetic permeability to electrical susceptibility in a vacuum.
Answer: Reciprocal of the speed of light in vacuum
(14) To which part of the spectrum does EM waves belong if the energy of the wave is of the order of 15 KeV.
[A] X rays
[B] Infrared rays
[C] Ultraviolet rays
[D] Gamma rays
Answer: X rays
(15) Which properties amount the following is false about electromagnetic waves?
[A] The energy in an electromagnetic wave is divided equally between electric and magnetic vectors.
[B] Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation of the wave.
[C] These waves do not require any material medium for propagation
[D] Both electric and magnetic field vectors attain the maxima and minima at the same place and the same time
Answer: Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation of the wave.
(16) In an electromagnetic wave in free space, the root mean square value of the electric field is 6 V/m. The peak value of the magnetic field is
[A] 2.83 x 10-8 T
[B] 1.51 x 10-8 T
[C] 0.80 x 10-8 T
[D] 4 x 10-8 T
Answer: 2.83 x 10-8 T
(17) In electromagnetic waves the phase difference between electric field vector and magnetic field vector is
[A] zero
[B] π/2
[C] π
[D] π/3
Answer: zero
(18) Which of the following can be used to produce a propagating electromagnetic wave?
[A] Charge moving at a constant speed
[B] Chargeless particle
[C] Stationary charge
[D] An accelerating charge
Answer: An accelerating charge
(19) Which of the following rays are not electromagnetic waves?
[A] Gamma rays
[B] Beta rays
[C] Heat rays
[D] X rays
Answer: Beta rays
(20) The direction in which electromagnetic waves propagate is the same as that of
[A]
[B]
[C]
[D]
Answer: A

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