Electricity, Magnetism & Induction

A circuit has constant voltage, but resistance increases. What happens to current?

Current decreases because increased resistance opposes electron flow; V = IR.

A circuit has constant resistance and the applied voltage increases. What happens to current?

Current increases because greater voltage provides more electrical push.

Which formula relates voltage, current, and resistance?

Ohm’s law

Which formula is used to calculate electrical power?

P = IV; power is measured in watts.

Why is alternating current required for normal transformer operation?

AC produces the continuously changing magnetic field needed to induce voltage.

How does direct current differ from alternating current?

DC flows in one direction; AC repeatedly changes direction.

What occurs around a conductor when electric current flows through it?

A magnetic field forms around the conductor.

Which relationship was demonstrated by Oersted?

Electric current produces a magnetic field.

Which relationship was demonstrated by Faraday?

A changing magnetic field can induce electrical voltage or current.

A magnetic field causes a piece of ferromagnetic material to become magnetized. What process occurred?

Magnetic induction.

A changing magnetic field produces voltage in a conductor. What process occurred?

Electromagnetic induction.

How does self-induction differ from mutual induction?

Self-induction occurs within the same coil; mutual induction occurs between two separate coils.

What is produced when current passes through a coil of wire wrapped around a ferromagnetic core?

An electromagnet.

What is the difference between magnetic susceptibility and magnetic permeability?

Susceptibility describes how easily a material becomes magnetized; permeability describes how readily magnetic field lines pass through or concentrate in it.

What does Lenz’s law state about an induced current?

The induced current produces an effect that opposes the change that caused it.