INDUCED POTENTIAL

What happens when an electrical conductor **(wire)** moves relative to a magnetic field

A potential difference is induced across the ends of the conductor

What is the requirement for an induced potential difference to cause a current flow

The conductor **(wire)** must form a closed loop or be part of a complete circuit

What are two ways that the generator effect is used to generate different types of current

Alternator: produce alternating-current

Dynamo: produce direct-current

What is the different between a dynamo and alternators

Dynamo has a split ring commutator

Alternators have split rings and brushes

What electromagnetic effect does a microphone take advantage of and how

* The generator effect
* It converts the pressure variations in sound waves into alternating current in a circuit

How can potential difference be induced into a wire

When the wire experiences a change in magnetic field a P.D. is induced across the wire

Moving it up and down through a magnetic field created by two magnets

How do alternators work

The coil of the wire rotates relative to the magnets

This induces a **magnetic field, voltage + current** in the coil

The slip rings + brushes mean the contacts **don’t** swap every half turn

Meaning they produce an **ALTERNATING** P.D + Current

What happens as the alternators coil rotates faster

The **frequency** and **amplitude increases**

How do dynamos work

The coil of the wire rotates relative to the magnets

This induces a **magnetic field, voltage + current** in the coil

The split ring commutator means that the contacts **swap** every half turn

They produce a **DIRECT** P.D and current

What happens as the dynamos coil rotates faster

The **frequency** and **amplitude increases**

When a wire stops moving through a magnetic field why does the P.D. disappear

The wire experiences a change in magnetic field as it moves the the field

This creates a P.D.

So when the wire stops moving there is no change in magnetic field therefore there is no P.D.

What happens to the direction of the P.D. as we change direction

It swaps, the + and - sides swap

What happens if you keep the wire still but still move the magnets

The wire is still experiencing a change in magnetic field creating an induced P.D. or current

Why is no P.D. created if we move the wire backwards/forwards

The wire isn’t experiencing a change in the magnetic field

How can we create a current with the generator effect

* Join the ends of the wire to create a circuit
* The electrons would be able to flow around the circuit, creating current

What are the **(3)** ways you can increase the size of induced P.D.

Change the strength of the magnetic field

Move the wire/magnets quicker

Shape the wire into a coil

How does changing the strength of the magnetic field increase P.D

Use stronger magnets:

**Stronger** magnets produce a **stronger magnetic field** which in turn produces a **larger potential difference**

How does moving the wires/magnets increase P.D

The faster the magnetics move the **faster the magnetic field will change**, the **bigger the induced P.D. is**

How does turning the wire into a coil increase P.D

The more turns the coil, the bigger the induced potential difference

How can you create a P.D./current in a coil

Moving the magnet in and out of the coil

Swapping the poles of the magnets

How does moving the magnet in and out of the coil

The coil is experiencing a change in magnetic field

The movement of the field

The circuit is complete it generates a current