Free Alternating Current MCQs with Answers
592 Alternating Current MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Alternating current varies periodically, so phase relationships become essential when current passes through a resistor, capacitor or inductor. The chapter distinguishes resistance from capacitive and inductive reactance, explains phase lead and lag, and connects changing electric and magnetic fields with the production and properties of electromagnetic waves.
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Read the Alternating Current notesFree MDCAT chapter notes with key terms592 questions · page 23 of 30
- A. 1 and 2
- B. 2 and 3
- C. 1, 2 and 3
- D. 2 only
Explanation: Since X-ray is an electromagnetic wave, they travel with same speed of light in the vacuum that is 3x106 m/s
Correct answer: 2 only- A. Two times
- B. Four times
- C. √2 times
- D. 8 times
Explanation: This is the following solution:D=√2hr where D=range of wave transmitted, h=height of the tower.Hence we can conclude that D is directly…
Correct answer: Four times- A. Power is transmitted along the magnetic field
- B. Power is transmitted along the electric field
- C. Power is equally transferred along the electric and magnetic fields
- D. Power is transmitted in a direction perpendicular to both the fields
Explanation: Since the propagation of the wave is in direction perpendicular both electric and magnetic field therefore the transmission of power is…
Correct answer: Power is transmitted in a direction perpendicular to both the fields- A. Parallel to each other
- B. Inclined at an angle of 45o
- C. Perpendicular to each other
- D. Opposite to each other
Explanation: The electric and magnetic fields (E and B) are in phase, and they are perpendicular to one another and the direction of propagation.
Correct answer: Perpendicular to each other- A. A charge moving with constant velocity
- B. A charge at rest
- C. A charge moving in a circular orbit
- D. Charges cannot produce an EM wave
Explanation: Charge moving in a circular orbit will have a variable acceleration as well as variable direction producing magnetic as well as electric…
Correct answer: A charge moving in a circular orbit446. The electromagnetic radiations are in descending order of wavelength in the following sequence:
- A. Infra-red waves, radio waves, X-rays, visible light rays
- B. Radio-waves, infra-red waves, visible light rays, X-rays
- C. Radio waves, visible light rays, infra-red waves, X-rays
- D. X-rays, visible light rays, infra-red wave, Radio-waves
Explanation: Radio-waves (103), infra-red waves (10-5), visible light rays (10-6), X-rays (10-10).
Correct answer: Radio-waves, infra-red waves, visible light rays, X-rays- A. 10-4 m
- B. 104 m
- C. 10-2 m
- D. 102 m
Explanation: This is the following solution: We use the formula v=fλ. For EMW v=c=3×10⁸m/s.
Correct answer: 10-4 m- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The value of total energy density of electromagnetic waves in vacuum = e0E2.
Correct answer: Option C- A. Infrared radiations
- B. Visible light
- C. Microwaves
- D. Ultraviolet rays
Explanation: Microwaves are radiations whose wavelengths pass through the Earth's atmosphere and can be used to transmit information to and from…
Correct answer: Microwaves- A. 3.5 m
- B. 5.5 m
- C. 7.5 m
- D. 9.5 m
Explanation: We use the formula v=fλ. For EMW v=c=3×10⁸m/s. Rearranging for λ and putting values we get,λ = c/f = 3×10⁸/40×10⁸ = 7.5m.Hence, this…
Correct answer: 7.5 m- A. 39.5 x 10^5
- B. 19.5 x 10^6
- C. 29.5 x 10^7
- D. 9 x 10^4
Explanation: This is the following solution:Radius of the area covered by T.V.telecastd=√2hRe Total population covered=πpd2×population density= 2πhRe ×…
Correct answer: 39.5 x 10^5- A. a<b,b<c
- B. a>b,b>c
- C. a>b, b>a
- D. a<b, b>c
Explanation: This is the following solution: a(frequency of X-rays =10¹⁸),b(frequency of gamma rays)=10²⁰and c(frequency of ultraviolet rays)=10¹⁶.
Correct answer: a<b, b>c- A. h1/2
- B. h
- C. h3
- D. h2
Explanation: This is the following solution:D=√2hr where D = range h= height of the tower and r = radius of the earth there D is directly proportional…
Correct answer: h1/2- A. 0.2 A
- B. 0.4 A
- C. 0.1 A
- D. Zero
Explanation: According to Ampere's Law, the sum of the conduction current and displacement current through any closed surface is zero.
Correct answer: 0.2 A- A. Radio waves
- B. X-rays
- C. Earthquake P-waves
- D. Gamma rays
Explanation: Radio waves, X-rays, gamma rays all lie in the electromagnetic spectra, at different frequencies and wavelength regions.
Correct answer: Earthquake P-waves- A. Parallel to electric field E
- B. Perpendicular to electric field E
- C. Antiparallel to Pointing vector S
- D. Random
Explanation: In an electromagnetic wave, the direction of the magnetic field induction B perpendicular to electric field E.
Correct answer: Perpendicular to electric field E- A. 20 m
- B. 30 m
- C. 40 m
- D. 10 m
Explanation: This is the following solution:Frequency =10 MHzSo wavelength =3×10⁸/10×10⁶=30m
Correct answer: 30 m- A. Halved
- B. Doubled
- C. Quardupled
- D. Kept unchanged
Explanation: Correct answer is 'doubled'.The relation between the height of the transmission antenna and the area covered by the TV telecast is given…
Correct answer: Doubled- A. 4 x 10^-6 T
- B. 6 x 10^-8 T
- C. 9 x 10^-9 T
- D. 11 x 10^-11 T
Explanation: This is the following solution:B0=E0/cSince B0=E0/c therefore B0=18/3×10⁸=6×10-8
Correct answer: 6 x 10^-8 T- A. Infrared
- B. Visible light
- C. Microwaves
- D. Ultraviolet rays
Explanation: Microwave radiation wavelengths pass through the Earth's atmosphere and can be used to transmit information to and from satellites in…
Correct answer: Microwaves