Generator Effect

What happens if we move a wire up through a magnetic field

Then a potential difference is induced across the ends to wire

What happens when wire stops moving

The P.D disappears

What happens if we move wire in opposite direction

Then the potential difference will be reversed

What is induced potential

Potential difference that’s reversed

When can you get an induced current

If there’s a complete circuit allowing Induced P.D to generate a current

What is the Generator effect

The induction of P.D(and current if there’s a complete circuit) in a wire which is moving relative to a magnetic field or experiencing a change in magnetic filed

When else can we get a induced P.D and current

If we keep the wire but still move the magnetic field as wire is experiencing a change in magnetic field

When can we only see the generator effect

If the wire passes through the magnetic field

What happens if wire moves along the magnetic field

Then we don’t get an induced P.D or current as wire isn’t experiencing a change in magnetic field

What factors increase the size of the Induced P.D or current

1)Stronger magnetic field as it means Larger induced P.D

2)Movind the wire rapidly as faster the magnetic field will change which means bigger induced P.D

3)Shaping the wire into a coil(the greater number of turns on the coil the greater the induced P.D and current)

When does the direction of the current change

When the direction of movement changes from a magnet through a coil

How can we switch the direction of the induced current in a wire

If we switch the poles of the magnet

What happens when we move a magnet into a coil of wire

A current is induced in the wire which creates its own magnetic field which opposes the movement of the magnet

What happens if we insert a North Pole into the coil

That end of the coil also becomes a North Pole which repels the magnet making it harder to push magnet in

What happens if we pull the North Pole out of coil

That end of coil become a South Pole which attracts magnet making it harder to pull it out

Since the induced current makes it hard to move magnet what are we doing

We are doing work as we are transferring energy from movement of magnet to movement of current

Where is the generator effect used in

An alternator to generate Alternating current and in a dynamo to generate direct current

What is a alternator

A Coil of Wire rotating in a magnetic field

What is the coil connected to

Two metal rings called commutators which allow the current to pass out of the coil

Describe where the red side and orange side connect to

Red side always connects onto ring A

Orange side always connects onto ring B

When is the maximum potential difference

When the coil is horizontal as the wire is sweeping through the magnetic filed lines as fastest possible rate

What way does the red side move and what way does the orange side move

Red side moves downwards and orange side moves upwards

When coil is vertical what happens to potential difference

The potential difference is zero as coil is moving parallel to the field so coil is not cutting through the magnetic filed lines

When would the potential difference reverse direction

When the two sides of the coil are now moving in a different direction to before as red side is moving up while orange side moves down

Because the two sides is the coil are attached to two different sides is rings…

An alternator produces an Alternating P.D and an alternating current(AC)

How can we increase size of alternating current

-Increasing strength of magnetic filed

-Incresing number of turns on coil

-Increasing area of coil

What happens if we increase the rotation speed of the coil

We also increase both the size and frequency of alternating current

What does a dynamo produce

A direct current

What is the key feature of a dynamo

It has a split ring commutator which as renamed separated by gaps

Which graph does this belong to

Dynamo

The part of the coil moving down belongs to which part and the side that is moving up belongs to which part

Side moving down is connected to part A of split ring commutator

Side of the coil that’s moving up belongs to side B

When coil is vertical what happens to P.D

Zero as coil is moving parallel to magnetic field

When the coil rotates in dynamo generator what happens to P.D and current direction

They do not reverse so we got a direct current

One full rotation in a coil means

Two peaks as each side of the coil passes through the magnetic field twice during each cycle of rotation, once passing down through the field and once passing up