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 19 of 59
- A. 4π x 10⁷ Wb A⁻¹ m⁻¹
- B. 4π x 10⁷ Wb A m⁻¹
- C. 4π x 10⁻⁷ Wb A⁻¹ m
- D. 4π x 10⁻⁷ Wb A⁻¹ m⁻¹
Explanation: μ₀ is the permeability of free space, a fundamental constant in electromagnetism.
Correct answer: 4π x 10⁻⁷ Wb A⁻¹ m⁻¹- A. The positive y direction
- B. Into the page
- C. The negative y direction
- D. Out of the page
Explanation: The electric force on a negative electron is opposite to the E-field, so it's in the +y direction.
Correct answer: Into the page- A. Half
- B. Remain same
- C. Double
- D. Zero
Explanation: Charge-to-mass ratio (e/m) of electron is fundamental constant property of particle itself.
Correct answer: Remain same- A. Zero
- B. Up
- C. Down
- D. East
Explanation: The magnetic force on a charged particle is given by F = qvB sin(θ), where θ is the angle between the velocity and the magnetic field.
Correct answer: Zero- A. Circles that are concentric with the wire
- B. Opposite to the direction of the current
- C. Radially outward from the wire
- D. Radially inward towards the wire
Explanation: The magnetic field lines created by a current in a long, straight wire form concentric circles in a plane perpendicular to the wire.
Correct answer: Circles that are concentric with the wire- A. Tends to get shorter
- B. Tends to rotate about its axis
- C. Tends to get longer
- D. Produces a zero magnetic field at its center
Explanation: A helical coil (solenoid) can be seen as a stack of parallel current loops.
Correct answer: Tends to get shorter367. If an electron and a proton enter into a magnetic field perpendicularly with the same momentum:
- A. The proton will deflect more
- B. Both will deflect equally
- C. The electron will deflect more
- D. They will not deflect at all
Explanation: The radius of the circular path of a charged particle in a magnetic field is given by r = p/(qB), where p is the momentum.
Correct answer: Both will deflect equally- A. Circular path
- B. Elliptical path
- C. Closed path
- D. Spherical path
Explanation: An Amperean path (or loop) is any imaginary closed path used in the application of Ampere's Law.
Correct answer: Closed path- A. Magnetic field strength
- B. Magnetic flux density
- C. Magnetic induction
- D. All of these
Explanation: Ampere's circuital law relates the line integral of the magnetic field around a closed loop to the total current passing through that…
Correct answer: All of these- A. An electric field only
- B. A magnetic field only
- C. Both an electric and a magnetic field
- D. No such field at all
Explanation: A stationary charge produces only an electric field. However, when a charge moves with a constant velocity, it constitutes a steady…
Correct answer: Both an electric and a magnetic field- A. Front part
- B. Back part
- C. Left wingtip
- D. Right wingtip
Explanation: Let +x = East, +y = North, +z = Up. Plane velocity v = South = −y. B = Down = −z.v × B = (−y) × (−z) = +x (East).
Correct answer: Right wingtip- A. F must be perpendicular to v but not necessarily to B
- B. F must be perpendicular to B but not necessarily to v
- C. v must be perpendicular to B but not necessarily to F
- D. F must be perpendicular to both v and B
Explanation: The formula describes a vector cross product. A fundamental property of the cross product is that the resulting vector (F) is always…
Correct answer: F must be perpendicular to both v and B- A. It will not move
- B. At an acute angle with the direction of current
- C. Perpendicular to the direction of current
- D. In the direction of current
Explanation: The force on a current-carrying wire in a magnetic field is given by F = ILBsinθ, where θ is the angle between the current and the field.
Correct answer: It will not move- A. North
- B. South
- C. East
- D. West
Explanation: Use right-hand rule: thumb current (west), fingers → magnetic field. At a point north of the wire, the field points south.
Correct answer: South- A. R
- B. 1/R
- C. 1/R2
- D. 1/R3
Explanation: According to Ampere's Law, the magnetic field (B) created by a long, straight wire is given by the formula B = μ₀I / (2πR).
Correct answer: 1/R- A. AC Current
- B. Pulsating DC current
- C. DC Current
- D. All of these
Explanation: Any movement of charge creates a magnetic field. Direct current (DC), alternating current (AC), and pulsating DC all involve the movement…
Correct answer: All of these- A. 2F/9
- B. 2F/3
- C. 4F/9
- D. 4F/3
Explanation: The force per unit length between two parallel wires is F ∝ (I₁I₂)/r. Initially, F ∝ I²/r.
Correct answer: 4F/3- A. Magnetic flux density
- B. Magnetic field lines
- C. Magnetic flux
- D. Both A and B
Explanation: Magnetic flux density (B) is a vector quantity because it has both magnitude and direction.
Correct answer: Magnetic flux density- A. Tend to cancel each other
- B. Reinforce each other
- C. Not affect each other
- D. Either 'A' or 'B'
Explanation: If currents are in the same direction, the fields in the middle oppose and weaken each other (causing attraction).
Correct answer: Either 'A' or 'B'- A. 1/R
- B. R2
- C. R
- D. R3
Explanation: The kinetic energy of the particle is KE = (1/2)mv². The speed of the particle at radius R is given by v = qBR/m.
Correct answer: R2