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 32 of 59
621. The secondary turns of which of the following transformers is always kept closed for _ transformer.
- A. Power
- B. Voltage
- C. Current
- D. Step down
Explanation: The secondary turns of a current transformer are always kept closed, forming a closed loop, and this allows the secondary current to…
Correct answer: Current- A. Monopole
- B. Dipole
- C. Quadrupole
- D. Octupole
Explanation: The current carrying loop behaves like a dipole having two poles north and south.
Correct answer: Dipole- A. 1.37 x 10^-7 W/m2
- B. 1.37 x 10^-5 W/m2
- C. 1.37 x 10^-1 W/m2
- D. 1.37 x 10^-2 W/m2
Explanation: Given: Length = L = 15 cm = 0.15 m Number of turns = N = 300 Current = I = 5 APermittivity of free space = μo = 4π × 10-7 Magnetic field…
Correct answer: 1.37 x 10^-2 W/m2- A. Increases emf
- B. Decreases emf
- C. Makes the emf zero
- D. Maintains the emf at a constant value
Explanation: Option A is correct since in an A.C. generator, the emf increases as the number of turns in the coil increases because the emf is directly…
Correct answer: Increases emf- A. 10V
- B. 20V
- C. 30V
- D. 4V
Explanation: The induced emf (ε) in a conductor moving at a velocity (v) perpendicular to a magnetic field (B) is given by the equation:ε = Bvlwhere l…
Correct answer: 10V- A. Electric field
- B. Magnetic field
- C. Both fields
- D. None of these
Explanation: If a charged particle is at rest and you are observing it from a moving train, the observer on the train will not see any magnetic field…
Correct answer: Both fields- A. Equal to(=)
- B. Less than(<)
- C. Greater than(>)
- D. Not equal
Explanation: A step down transformer produces a smaller output voltage than the input voltage provided to it.
Correct answer: Less than(<)- A. Both momentum and energy of particle change
- B. Momentum as well as energy are constant
- C. Energy is constant but momentum changes
- D. Momentum is constant but energy changes
Explanation: If a charged particle moves through a magnetic field perpendicular to it, it acquires circular motion.
Correct answer: Energy is constant but momentum changes- A. 314 Wb
- B. 107 Wb
- C. 157 Wb
- D. 435 Wb
Explanation: Correct Option: CTo find the corresponding flux through the loop, we can use the formula:Flux (Φ) = B * A * cos(θ)Where:B is the magnetic…
Correct answer: 157 Wb- A. Electrostatic
- B. Magnetic
- C. Electromagnetic
- D. None of these
Explanation: When a current changes over time, it generates an electromagnetic field, which combines both electric and magnetic fields that vary…
Correct answer: Electromagnetic- A. Vs/Vp =1
- B. Vs<Vp
- C. Vs=Vp
- D. Vs>Vp
Explanation: Correct Option: DThis option is correct because in the step up transformers the number of the voltage in the secondary coil is greater…
Correct answer: Vs>Vp- A. Inductance
- B. Induced current
- C. Induced flux
- D. Induced magnetic field
Explanation: Correct Option: BThis option is correct because lenz's law provides information regarding the induced current.It tells about the direction…
Correct answer: Induced current- A. Voltage
- B. Electric field
- C. Magnetic field
- D. All of these
Explanation: According to Faraday's law, an increase in the number of loops will result in an increase in the induced EMF or voltage.
Correct answer: Voltage- A. Is=10Ip
- B. Ns=Np/10
- C. Ns=10Np
- D. Vs=Vp/10
Explanation: The turns ratio of a transformer describes the number of wire turns on the input versus the number of turns on the output.
Correct answer: Ns=10Np- A. Armature
- B. Magnet
- C. Slip rings
- D. Commutator
Explanation: AC generator does not have commutators. DC generators have commutators to make the current flow in one direction only.
Correct answer: Commutator- A. Minimum
- B. Constant
- C. Zero
- D. Maximum
Explanation: This can be achieved by ensuring that the coils are placed close to each other and that they have a high number of turns.
Correct answer: Maximum- A. Silicon steel
- B. Soft iron
- C. Aluminium
- D. Cast steel
Explanation: Silicon steel is used for transformer core laminations because it has low hysteresis loss, which helps in reducing energy losses in the…
Correct answer: Silicon steel- A. Core length increases
- B. Core area increases
- C. Flux density decreases
- D. Flux density increases
Explanation: The attraction capacity of the electromagnet will increase if the flux density increases.
Correct answer: Flux density increases- A. Electromagnetic friction
- B. Electromagnetic force
- C. Electromagnetic function
- D. None of these options are correct
Explanation: According to Faraday's law, EMF stands for Electromotive force.Faraday's law of electromagnetic induction states that a change in the…
Correct answer: None of these options are correct- A. Increased core loss
- B. Increased I2R loss
- C. Interference with communication circuits
- D. All of these options are correct
Explanation: Harmonics in a transformer can result in all of the given options being correct.
Correct answer: All of these options are correct