Free Lenz's Law MCQs with Answers

• A. assists the change producing it
• B. opposes the change producing it
• C. is always clockwise
• D. is independent of the change

Explanation: The induced current sets up a field that opposes the flux change, so pushing a north pole towards a coil induces a current making the near…

• A. that the emf is always negative
• B. Lenz's law, that the induced effect opposes the change causing it
• C. that flux always decreases
• D. an error of convention with no physical meaning

Explanation: The sign encodes the direction of the induced emf rather than its magnitude, stating that it acts to oppose the change in flux.

• A. copper is magnetic and attracts it
• B. air resistance inside the tube is very large
• C. induced eddy currents in the tube produce a field opposing the magnet's motion
• D. the magnet loses its magnetism as it falls

Explanation: The changing flux induces circulating eddy currents in the tube wall, and by Lenz's law their magnetic field opposes the motion, retarding…

• A. adds to the supply voltage
• B. opposes the supply voltage and limits the current drawn
• C. has no effect on the current
• D. appears only when the motor is stationary

Explanation: As the armature spins it acts as a generator, inducing an emf that by Lenz's law opposes the supply, so the effective driving voltage and…

• A. is attracted into the coil
• B. is thrown upwards, because the induced current opposes the changing flux
• C. remains unaffected
• D. melts instantly

Explanation: The changing flux induces a current in the closed ring, and by Lenz's law the ring's field opposes the coil's, so the two repel and the…

• A. the magnetic field, which is used up
• B. the mechanical work done against the opposing force predicted by Lenz's law
• C. nothing, since it is created by induction
• D. the resistance of the circuit

Explanation: Because the induced effect opposes the motion, whoever moves the magnet or turns the generator must do work, and that mechanical work is…

• A. Enhance the motion
• B. Try to stop the approach
• C. Become zero
• D. Become alternating

Explanation: By Lenz's law the induced current sets up a field that opposes the change producing it, so the loop is repelled and work must be done to…

• A. Each increase
• B. Each decrease
• C. Each remains the same
• D. One increases whereas that in the other decreases

Explanation: As the loops approach, the magnetic flux through each loop increases. By Lenz's law, the induced effect opposes this increase, producing a…

• A. Lenz's law.
• B. Faraday's law.
• C. Ampere's law.
• D. Coulomb's law.

Explanation: Lenz's law is the correct answer because it specifically addresses the direction of induced e.m.f.

• A. Mass
• B. Energy
• C. Charge
• D. Momentum

Explanation: Lenz's law is based on the law of conservation of energy. From the definition of Lenz's law, we know that the induced current is always…

• A. Charge
• B. Mass
• C. Energy
• D. Pressure

Explanation: Lenz's law is also a statement of the law of conservation of energy. It articulates that the direction of the induced electromotive force…

• A. emf.
• B. Resistance.
• C. Shear
• D. Currents.

Explanation: Lenz's law refers to induced currents and not to induced EMF, which means that we can apply it directly to closed conducting loops or…

• A. resotoring torque
• B. defelection torque
• C. back motor effect
• D. all of these

Explanation: When the current I passes through the coil, the coil experiences torque, which rotates the coil through an angle alpha.

• A. Charge
• B. Current
• C. Energy
• D. Magnetic field

Explanation: Lenz's law exemplifies the law of conservation of energy. It states that the induced electromotive force (emf) in a closed loop will…

• A. Ohm's law
• B. Coulomb's law
• C. Lenz's law
• D. Newton's law of motion

Explanation: Lenz's law of electromagnetic induction states that the direction of the current induced in a conductor by a changing magnetic field is…

• A. Law of conservation of current
• B. Law of conservation magnetization
• C. Law of conservation of charges
• D. Law of conservation of energy

Explanation: Lenz's Law is a fundamental principle in electromagnetism. It states that when there is a change in the magnetic field through a…