electromagnetic induction...• electromagnetic induction is the term used to describe how...

ELECTROMAGNETIC INDUCTION

Book pg 189 – 192

Syllabus 6.15 – 6.16

© www.cgrahamphysics 2015

STARTER

v On your Ipad explain how electricity is generated


KEYWORDS: Electromagnetic induction, Generator, coil, wire, magnet

Understand how generators create

electricity

ALL – State how electricity can be created MOST – Describe how electromagne6c induc6on can be increased SOME – Explain generators work in detail


MOTOR VS GENERATOR

v Motors use electricity to produce movement

v Generator make electricity from movement


•  Electromagnetic induction is the term used to describe how electricity is created in a wire.

•  Moving a magnet in a coil of wire is ONE of only TWO ways that humans know how to generate electricity

•  The other way is moving a wire in a magnetic field

LO: Understand how generators create electricity

ELECTROMAGNETIC INDUCTION


6 of 22 © Boardworks Ltd 2012

What is electromagnetic induction?

If a wire is moved across a magnetic field, a potential difference is induced across the wire and a current is produced. This is electromagnetic induction.

Induction also occurs if a magnet is moved in a coil of wire, or if a coil of wire rotates in a magnetic field.

In all these methods of inducing a current, the wire and magnetic field move perpendicular to each other. If they move parallel to each other, no current is induced.


Inducing current in a wire


Electromagnetic induction depends on relative movement between the magnet and the coil.

If there is no movement, then there will be no electromagnetic induction and no voltage produced across the ends of the coil.

Magnet and coil: relative movement

It doesn’t matter whether it is the coil (top) or the magnet (bottom) that is moving.


Inducing current in a coil


Varying the size of the induced voltage


Factors affecting induced current

v Moving the wire more quickly

v Using a stronger magnet

v Wrapping the wire into a coil so

that more pieces of wire move

through the magnetic field

v Moving the magnet more quickly

v Using a stronger magnet

v Using a coil with more turns

SUMMARY: H OW T O I N C R E A S E T H E I N D U C E D V O LT A G E

Moving a coil in a magnetic field Moving a magnet into a coil


STRENGTH OF CURRENT v  A voltage and current are generated when a conductor cuts through a magnetic

field

v  The faster the lines are cut, the larger the induced voltage and current

v  No cutting à no voltage or current

v  If direction of motion is reversed, the direction of induced current is reversed

v  Maximum cutting when the coil is parallel to the field à maximum current induced

v  No cutting when the coil is at 90↑0  to the field

à no current induced



How do AC generators work?


AC generator simulation

WHAT IS THE DIFFERENCE BETWEEN DC AND AC



Plenary: True or false?

electromagnetic induction...• electromagnetic induction is the term used to describe how...

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