Free Electromagnetism MCQs with Answers
1,176 Electromagnetism MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.
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Read the Electromagnetism notesFree MDCAT chapter notes with key terms1,176 questions · page 31 of 59
- A. Mutual induction
- B. Self induction
- C. Motional emf
- D. None of these
Explanation: Option A is correct as when a transformer's primary coil has an AC flowing through it; magnetic flux surrounds the conductor in proportion…
Correct answer: Mutual induction602. Force on a moving charge in a uniform magnetic field will be maximum when angle between v and B is?
- A. Zero
- B. 30
- C. 60
- D. 90
Explanation: Option D is correct as the formula to find force in a magnetic field is F=Bqv Sin(theta).
Correct answer: 90- A. 1.6 Wb
- B. 0.16 Wb
- C. 16 Wb
- D. 0 Wb
Explanation: Magnetic flux can be calculated using the formula: Φ = B x A Where B refers to the magnetic field stength (0.1T) and A refers to the area…
Correct answer: 1.6 Wb- A. Vs/Vp = 1
- B. Vs < Vp
- C. Vs=Vp
- D. Vs > Vp
Explanation: Step-up transformer is a transformer that increases the voltage from primary to secondary. Hence "Vs>Vp".
Correct answer: Vs > Vp- A. Maximum
- B. Minimum
- C. Zero
- D. To independent of current
Explanation: The current is 0 when the coil is vertical (perpendicular to the magnetic field).
Correct answer: Maximum- A. Positive
- B. Zero
- C. Negative
- D. None of these
Explanation: The magnetic force acts in such a way that the direction of the magnetic force and velocity are always perpendicular to each other.If…
Correct answer: Zero- A. 50%
- B. 1
- C. 20%
- D. 10%
Explanation: The formula for the efficiency of a transformer is given by, Efficiency η = Output power / input power X 100 = output power / output power…
Correct answer: 50%- A. Mica strip
- B. Paper
- C. Thin coating of Varnish
- D. Any of the above
Explanation: These laminations are insulated from each other by a "thin coat of varnish" or paper to increase the effective resistivity of the core…
Correct answer: Thin coating of Varnish- A. Yes
- B. No
- C. Depends on strength of field
- D. Only when the field is large
Explanation: Magnetic flux lines are imaginary lines drawn solely for a better understanding of magnetic flux.
Correct answer: No- A. Equal to
- B. Greater than
- C. Less than
- D. None of these
Explanation: Correct. In an ideal step-up transformer, there is no power loss, meaning the power input (Pp) equals the power output (Ps).
Correct answer: Equal to- A. Cast iron
- B. Silicon steel
- C. Aluminium
- D. Cast steel
Explanation: Eddy currents passing through the core of a transformer due to the induced voltages can cause heat loss.
Correct answer: Silicon steel- A. Core length increases
- B. Core area increases
- C. Flux density decreases
- D. Flux density increases
Explanation: Flux density represents the number of magnetic field lines passing through a cross section.
Correct answer: Flux density increases- A. henry
- B. henry/m
- C. Dimensionless
- D. henry/sq. m
Explanation: Relative Permeability, μr, is given as the ratio of permeability of vacuum μ to the permeability of the medium μm.The formula is given…
Correct answer: Dimensionless- A. 160 weber
- B. 100 weber
- C. 40 weber
- D. 80 weber
Explanation: Area of square loop (A)= (length)2= 42= 16m2Magnetic field strength (B) = 10TAngle (θ) = 600 Φ= BA cosθ = 10 x 16 x cos600 = 160 x 0.5 =…
Correct answer: 80 weber- A. Lagging
- B. Leading
- C. Unity
- D. any of above
Explanation: a) Lagging: In a transformer, the voltage regulation is said to be negative when the secondary voltage decreases with an increase in the…
Correct answer: Lagging- A. 0.8 wb
- B. 8 wb
- C. 0.008 wb
- D. 0.08 wb
Explanation: B, that stands for the magnetic field strength= (0.3i + 0.4j) T.A vector, that stands for the area vector, comprises of the Area, in…
Correct answer: 0.008 wb- A. Positive
- B. Zero
- C. Negative
- D. None of these
Explanation: Option C is correct since flux is the dot product of field vectors and area vectors.
Correct answer: Negative- A. Deflect upwards
- B. Deflect downwards
- C. Speed up
- D. Speed down
Explanation: Option C is correct since over here the velocity vector and magnetic field vector are in the same direction so there is no magnetic force.
Correct answer: Speed up- A. 2 : 3
- B. 3 : 2
- C. 4 : 9
- D. 9 : 4
Explanation: FC = FM mv2/r = qvB r = mv/qB r1/r2 = v1/v2 Given; v1/v2 = 3/2 So; r1/r2 = 3/2 The ratio of the radii of the circular paths of two charged…
Correct answer: 3 : 2- A. 1:2
- B. 1:3
- C. 2:1
- D. 2:5
Explanation: A step-down transformer is designed to reduce the voltage of the input signal.
Correct answer: 2:1