The potential difference generated in a conductor moving relative to a magnetic field.

An electric current that consistently flows in one direction.

An electric current that repeatedly reverses direction.

Electric generators

Physics

In the Magnets and electromagnets unit, pupils learnt about rules for magnets, magnetic fields of bar magnets, and the properties and uses of electromagnets. 

Electromagnetism

Current that always goes in the same direction is called {{}} current.

A device that produces AC in a rotating coil.

A device that makes a current-carrying coil rotate.

A device that produces DC in a rotating coil.

Match each key term with the correct description.

The thumb represents the direction of motion.

The second finger represents the magnetic field direction.

This rule is used to find the direction of an induced current.

This rule is used to find the direction of movement in the motor effect.

Which of the following statements about Fleming’s right–hand rule are correct?

The diagrams show a wire loop in a magnetic field with direction shown by the grey arrow. The wire is pushed as shown by black arrows. It is part of a circuit. In which diagram is no current induced? 

It produces a current that does not change.

It can have exactly the same design as a motor, with a handle added.

Increasing the number of turns in the coil increases the induced potential.

Which of the following statements about a dynamo are correct?

The orange side of the coil will always be on the right.

The orange side of the coil will always move upwards.

The orange side of the coil will never touch the right–hand contact.

The current in the orange side will always be in the same direction.

The diagram shows an alternator’s magnets and coil (but no other parts). One side of the coil is painted orange; it is on the right, touches the left contact, and moves up. Which statement is correct?

The field line arrows point from left to right.

The field line arrows point from right to left.

The field lines are parallel to each other.

The field lines are perpendicular to each other.

Two magnets have their poles on their large, flat faces. They are positioned as shown in the diagram. Which of the following statements about the magnetic field between them are correct?

Which of the following diagrams show a uniform magnetic field between two magnets?

an induced potential and an induced current at the same time

an induced current without an induced potential

an induced potential without an induced current

Which of the following can be caused by moving a wire through a magnetic field?

increasing the number of turns in the coil

A pupil induces a current in a coil by moving a magnet into the coil. Which of the following changes would increase the induced current?

leaving the wire stationary in the magnetic field

moving the wire parallel to the magnetic field lines

moving the wire perpendicular to the magnetic field lines

Which of the following actions induces a potential across a wire that is in an unchanging magnetic field?

The current is always in the same direction.

Current goes from the positive terminal around the circuit to the negative.

If the resistor is changed, the current in the battery changes.

If the resistor is changed, the potential difference across the battery changes.

A simple circuit has a resistor connected to a battery. The resistor does not heat up significantly. Which of the following statements are correct?

Starter Quiz