Physics 2- Chapter 23

What is electromagnetic induction?

The process of generating an electromotive force (emf) through a change in magnetic flux.

Who independently demonstrated that magnetic fields can produce currents?

Michael Faraday and Joseph Henry.

What is the relationship between a changing magnetic field and induced emf?

Any change in magnetic flux induces an emf.

What is Faraday’s law of induction?

The induced emf in a closed loop is directly proportional to the rate of change of magnetic flux through the loop.

What does Lenz's Law state?

The direction of induced current is such that it opposes the change in magnetic flux that produced it.

What is the Hall effect?

The generation of a voltage across an electrical conductor when a magnetic field is applied perpendicular to the current flow.

What are eddy currents?

Looping currents that are induced in conductors by a changing magnetic field, resulting in magnetic damping.

What is a transformer?

A device that changes the voltage of alternating current in a circuit.

What is self-inductance?

The phenomenon where a changing current in a coil induces an emf in the same coil.

What is the formula for the energy stored in an inductor?

The energy stored is given by U = 1/2 L I^2, where L is inductance and I is the current.

How does varying magnetic flux occur in a generator?

By rotating a coil within a magnetic field, which changes the magnetic flux through the coil.

What is back emf in a motor?

The emf generated by a motor that opposes the input voltage, affecting current draw.

What is mutual inductance?

The phenomenon in which a change in the electric current in one coil induces an emf in another coil.

Why are transformers unable to operate on direct current (DC)?

Because DC does not produce a changing magnetic field, hence no induced emf is generated in the secondary.

What is meant by the term 'magnetic damping'?

A reduction in oscillation or motion caused by eddy currents induced in a conductor.

What is the role of a ground fault interrupter (GFI)?

To compare the currents in live and neutral wires and trip the circuit if there is a leakage current.

What is the difference between a step-up and step-down transformer?

A step-up transformer increases voltage while a step-down transformer decreases voltage.

What is the unit of inductance?

Henry (H).

How does electromagnetic induction relate to recycling?

Eddy currents and magnetic damping allow for the separation of metals from nonmetals at recycling centers.