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.
Last updated
Read the Electromagnetism notesFree MDCAT chapter notes with key terms1,176 questions · page 22 of 59
- A. A
- B. B
- C. C
- D. D
Explanation: As we know F = qvB sin θ. Where θ is the angle between the velocity and the magnetic field, a greater angle leads to maximum force.
Correct answer: C- A. Clockwise
- B. Anticlockwise
- C. Along PQ
- D. Does not rotate
Explanation: If the given arrangement lies in a horizontal plane, then the rod PQ will rotate clockwise due to the torque.
Correct answer: Clockwise- A. B to A
- B. A to B
- C. There is no current
- D. Cannot be determined
Explanation: Increasing the resistance causes a decrease in the current on the left. This reduces the field strength for the solenoid B=µonI.
Correct answer: B to A- A. πm/2qB
- B. πm/qB
- C. πm/4qB
- D. πm/3qB
Explanation: The explanation is given in the image below:
Correct answer: πm/qB- A. 1.935
- B. 0.075
- C. 0.175
- D. 2.375
Explanation: The relative permeability μr is related to magnetic susceptibility Xm by the equation μr = 1 + Xm.
Correct answer: 0.075- A. Aid the change in magnetic flux
- B. Oppose the change in magnetic flux
- C. Be parallel to the magnetic field
- D. Be independent of the magnet's motion
Explanation: Lenz's Law states that the induced current will flow in a direction that opposes the change in magnetic flux that caused it (energy…
Correct answer: Oppose the change in magnetic flux- A. 4:1
- B. 1:4
- C. 2:1
- D. 1:2
Explanation: For a circuar coil, the magnetic field at the centre is B = μoI/ 2r, where I is the current and r is the radius.
Correct answer: 1:4- A. L2 I / 4π N2
- B. L2NI / 4π
- C. L2 I / 4πN
- D. L2IN2 / 4π
Explanation: The magnetic moment (M) of a coil is given by M = NIA, where A is the area of one turn.
Correct answer: L2 I / 4πN- A. 1.97 × 10⁻³ m
- B. 3.94 × 10⁻³ m
- C. 5.91 × 10⁻³ m
- D. 7.88 × 10⁻³ m
Explanation: Pitch = vT, where v= v cosθ = 5 × 10⁶ × cos 30° = 4.33 × 10⁶ m/s, T = 2πm/(qB) = (2π × 9.1 × 10⁻³¹)/(1.6 × 10⁻¹⁹ × 0.4) ≈ 8.94 × 10⁻¹⁰ s.
Correct answer: 3.94 × 10⁻³ m- A. 0.75 A
- B. 1.5 A
- C. 2.25 A
- D. 3 A
Explanation: Motional emf = ε = NBvl, where N = 10, B = 0.6 T, v = 8 m/s, l = 0.25 m. Thus, ε = 10 × 0.6 × 8 × 0.25 = 6 V. Current I = ε/R = 6/4 = 1.5 A.
Correct answer: 1.5 A- A. 4 × 10⁻⁶ T
- B. 8 × 10⁻⁶ T
- C. 12 × 10⁻⁶ T
- D. 16 × 10⁻⁶ T
Explanation: Distance r = √(0.3² + 0.4²) = 0.5 m. Magnetic field B = (μ₀I)/(2πr) = (4π × 10⁻⁷ × 20)/(2π × 0.5) = 8 × 10⁻⁶ T.
Correct answer: 8 × 10⁻⁶ T- A. 2 × 10³ rad/s
- B. 4 × 10³ rad/s
- C. 6 × 10³ rad/s
- D. 8 × 10³ rad/s
Explanation: Angular frequency ω = qB/m. Substituting q = 3 × 10⁻⁶ C, B = 0.25 T, m = 6 × 10⁻⁵ kg. ω = (3 × 10⁻⁶ × 0.25)/(6 × 10⁻⁵) = 4 × 10³ rad/s.
Correct answer: 4 × 10³ rad/s- A. 37.7 V
- B. 75.4 V
- C. 113.1 V
- D. 150.8 V
Explanation: Maximum emf = NBAω, where N = 25, B = 0.4 T, A = 0.1 × 0.15 = 0.015 m², ω = 2πf = 2π × (2400/60) = 80π rad/s.
Correct answer: 75.4 V- A. Remains stationary
- B. Move towards each other
- C. Move away from each other
- D. Move at right angles to each other
Explanation: When two parallel wires carry current in the same direction, they exert equal and opposite attractive forces on each other.
Correct answer: Move towards each other- A. Straight
- B. Circular
- C. Curve
- D. Helical
Explanation: When an electron enters a magnetic field at an angle less than 90 degrees, its velocity can be decomposed into components: one parallel…
Correct answer: Helical- A. At an angle of 180 degrees with the galvanometer
- B. Parallel with galvanometer
- C. At an angle of 45 degrees With the galvanometer
- D. Perpendicular with the galvanometer
Explanation: Since Galvanometer is a very sensitive instrument therefore it can't measure heavy currents.
Correct answer: Parallel with galvanometer- A. Energy
- B. Charge
- C. Momentum
- D. Mass
Explanation: Lenz's law is used to determine the direction of the induced current by a change in magnetic field.
Correct answer: Energy- A. Nature of the material of the conducting wire
- B. Area of the conducting wire
- C. Amount of the current
- D. Direction of the current
Explanation: The direction of the magnetic force depends on the direction of the current and the direction of the magnetic field.
Correct answer: Direction of the current- A. Beam of electrons will be negative due to magnetic field.
- B. Beam of electrons will be zero due to magnetic field.
- C. Beam of electrons will be reflected due to magnetic field.
- D. Beam of electrons will be deflected due to magnetic field.
Explanation: TVs basically work by releasing beams of electrons on a screen giving us the picture.
Correct answer: Beam of electrons will be deflected due to magnetic field.- A. Reduces by factor 2
- B. Becomes double
- C. Reduces by factor 4
- D. Becomes triple
Explanation: Any current-carrying wire is surrounded by the magnetic field which is B = µ0I/2πr.
Correct answer: Reduces by factor 2