Revision Questions: Topic 20.5 EMF Induction

What is Faraday's law of electromagnetic induction?

• A change in density induces an electromotive force (EMF) in a conductor.

• A change in temperature induces an electromotive force (EMF) in a conductor.

• A change in pressure induces an electromotive force (EMF) in a conductor.

• A change in magnetic field induces an electromotive force (EMF) in a conductor.

State the mathematical expression for Faraday's law of electromagnetic induction.

• emf = N(Φ/dt)

• emf = -N(Φ/dt)

• emf = N(dΦ/dt)

• emf = -N(dΦ/dt)

Explain the concept of induced emf as per Faraday's law.

• The induced emf is the result of a constant magnetic field on a stationary conductor.

• The induced emf is the voltage produced in a conductor by a steady magnetic field.

• The induced emf is the electromotive force generated in a conductor by a changing magnetic field.

• The induced emf is the force generated in a conductor by a static magnetic field.

Describe an experiment to demonstrate Faraday's law of electromagnetic induction.

• Place the coil of wire in direct sunlight

• Move a magnet in and out of a coil of wire connected to a galvanometer.

• Blow air onto the coil of wire

• Shake the coil of wire vigorously

What is Lenz's law and how does it relate to electromagnetic induction?

• Lenz's law explains the speed of light in a vacuum

• Lenz's law describes the behavior of sound waves in air

• Lenz's law is unrelated to electromagnetic induction

• Lenz's law explains the direction of the induced current or emf in a circuit when there is a change in magnetic flux.

State Lenz's law and explain its significance in the context of electromagnetic induction.

• The significance of Lenz's law in the context of electromagnetic induction is that it helps to determine the direction of the induced current in a circuit, and it ensures that energy is conserved in the process of electromagnetic induction.

• Lenz's law determines the speed of the induced current in a circuit

• Lenz's law only applies to certain types of materials

• Lenz's law has no significance in the context of electromagnetic induction

How does Lenz's law determine the direction of induced current in a circuit?

• It determines the direction of induced current by flowing in a direction that opposes the change in magnetic flux.

• It determines the direction of induced current by flowing in the same direction as the change in magnetic flux.

• It determines the direction of induced current by flowing in the opposite direction of the change in magnetic flux.

• It determines the direction of induced current by flowing in a random direction.

Explain the concept of motional emf and its relationship with magnetic fields.

• Motional emf is inversely proportional to the magnetic field strength

• Motional emf is the voltage induced in a conductor at rest in a magnetic field

• Motional emf is the voltage induced in a conductor moving through a magnetic field, and it is directly proportional to the magnetic field strength, the length of the conductor, and the velocity of the conductor.

• Motional emf is not affected by the length of the conductor

Derive the equation for motional emf in a straight conductor moving through a magnetic field.

• emf = B - l * v

• emf = B + l + v

• emf = B * l * v

• emf = B * l / v

Describe an application of motional emf in real-life scenarios.

• Generators

• Mobile phone chargers

• Refrigerators

• Traffic lights