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ELECTRICITY, MAGNETISM AND ELECTROMAGNETISM.

Electricity, magnetism and electromagnetism

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Electricity, magnetism and electromagnetism

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Page 1: Electricity, magnetism and electromagnetism

ELECTRICITY, MAGNETISM AND

ELECTROMAGNETISM.

Page 2: Electricity, magnetism and electromagnetism

ATOMS…

Have neutrons, protons, and electrons.

Protons are positively charged

Electrons are negatively charged

Page 3: Electricity, magnetism and electromagnetism

ELECTRONS…

Are located on the outer edges of

atoms…they can be moved.

A concentration of electrons in an atom

creates a net negative charge.

If electrons are stripped away, the atom

becomes positively charged.

Page 4: Electricity, magnetism and electromagnetism

+-

+

+

++

THE WORLD IS FILLED WITH ELECTRICAL

CHARGES:

+

+

+

+

+

-

-- -

-

-

- --

Page 5: Electricity, magnetism and electromagnetism

STATIC ELECTRICITY

The build up of an electric charge on the surface of an object.

The charge builds up but does not flow.

Static electricity is potential energy. It does not move. It is stored.

Page 6: Electricity, magnetism and electromagnetism

STATIC DISCHARGE…

Occurs when there is a loss of static

electricity due to three possible things:

Friction - rubbing

Conduction – direct contact

Induction – through an electrical field

(not direct contact)

Page 7: Electricity, magnetism and electromagnetism
Page 8: Electricity, magnetism and electromagnetism

ELECTRICITY THAT MOVES…

Current: The flow of electrons from one

place to another.

Measured in amperes (amps)

Kinetic energy

Page 9: Electricity, magnetism and electromagnetism

HOW CAN WE CONTROL CURRENTS?

With circuits.

Circuit: is a path for the flow of electrons.

We use wires.

Page 10: Electricity, magnetism and electromagnetism

Static electricity is stationary or collects on the surface of

an object, whereas current electricity is flowing very

rapidly through a conductor.

Page 11: Electricity, magnetism and electromagnetism

The flow of electricity in current electricity has

electrical pressure or voltage. Electric

charges flow from an area of high voltage to

an area of low voltage.

Page 12: Electricity, magnetism and electromagnetism

Water pressure and voltage behave in

similar ways.

Page 13: Electricity, magnetism and electromagnetism

THERE ARE 2 TYPES OF CURRENTS:

Direct Current (DC) – Where electrons

flow in the same direction in a wire.

Page 14: Electricity, magnetism and electromagnetism

THERE ARE 2 TYPES OF CURRENTS:

Alternating Current (AC) – electrons

flow in different directions in a wire

Page 15: Electricity, magnetism and electromagnetism

THERE ARE 2 TYPES OF CIRCUITS:

Series Circuit: the components are lined

up along one path. If the circuit is

broken, all components turn off.

Page 16: Electricity, magnetism and electromagnetism

SERIES CIRCUIT

Page 17: Electricity, magnetism and electromagnetism

THERE ARE 2 TYPES OF CIRCUITS:

Parallel Circuit – there are several

branching paths to the components. If

the circuit is broken at any one branch,

only the components on that branch will

turn off.

Page 18: Electricity, magnetism and electromagnetism

PARALLEL CIRCUIT

Page 19: Electricity, magnetism and electromagnetism

CONDUCTORS VS. INSULATORS

Conductors – material through which

electric current flows easily.

Insulators – materials through which

electric current cannot move.

Page 20: Electricity, magnetism and electromagnetism

EXAMPLES

Conductors:

Metal

Water

Insulators:

Rubber

Plastic

Paper

Page 21: Electricity, magnetism and electromagnetism

WHAT IS RESISTANCE?

The opposition to the flow of an electric current, producing heat.

The greater the resistance, the less current gets through.

Good conductors have low resistance.

Measured in ohms.

Page 22: Electricity, magnetism and electromagnetism

WHAT IS VOLTAGE?

The measure of energy given to the

charge flowing in a circuit.

The greater the voltage, the greater the

force or “pressure” that drives the

charge through the circuit.

Page 23: Electricity, magnetism and electromagnetism

OHM’S LAW

Resistance = Voltage / Current

Ohms = Volts / Amps

V= IR I =V/R R=V/I

Page 24: Electricity, magnetism and electromagnetism

MAGNETISM

Page 25: Electricity, magnetism and electromagnetism

What is magnetism?Magnetism is the properties and interactions of magnets

The earliest magnets were found naturally in the mineral magnetite which is abundant the rock-type lodestone. These magnets were used by the ancient peoples as compasses to guide sailing vessels.

Page 26: Electricity, magnetism and electromagnetism

Magnets produce magnetic forces and have

magnetic field lines

Page 27: Electricity, magnetism and electromagnetism

The earth is like a giant magnet!

The nickel iron core of the earth gives the earth a

magnetic field much like a bar magnet.

Page 28: Electricity, magnetism and electromagnetism

MAGNETS

USUALLY MADE OF IRON

EVERY MAGNET HAS A NORTH AND SOUTH

POLES

LIKE SIMILAR CHARGES REPEL

OPPOSITES ATTRACT

Page 29: Electricity, magnetism and electromagnetism

FERROMAGNETIC

OBJECTS THAT CAN BE MAGNETIZED

(IRON, COBALT, NICKEL)

3 TYPES OF MAGNETS

LODESTONE – NATURAL (PERMANENT)

ARTIFICAL – INDUCED

ELECTROMAGNET – temporary magnets

produced by moving electric current

Page 30: Electricity, magnetism and electromagnetism
Page 31: Electricity, magnetism and electromagnetism

Ferromagnetic

material such as iron

attracts magnetic

lines of induction,

whereas nonmagnetic

material such as

copper does not.

Page 32: Electricity, magnetism and electromagnetism

Demonstration of

magnetic lines of

force with iron filings

NORTH &

SOUTH POLES

Page 34: Electricity, magnetism and electromagnetism

A moving charge creates a magnetic field

When a charged particle is in motion – a magnetic force field perpendicular to the motion is created

Page 35: Electricity, magnetism and electromagnetism

ELECTROMAGNETISM

Page 36: Electricity, magnetism and electromagnetism

ELECTROMAGNETISM

A MOVING CHARGE CREATES A MAGNETIC

FIELD

Page 37: Electricity, magnetism and electromagnetism

RT HAND RULE

Current flow direction of thumb

Magnetic filed – fingers

Page 38: Electricity, magnetism and electromagnetism

ELECTROMAGNET IS CREATED BY:

SOLENOID: Current flowing

through coil of wire

Putting a magnet in the

middle of the coil of wire

increases the strength of the

electromagnet’s magnetic

field

Page 39: Electricity, magnetism and electromagnetism

A coil of wire is a helix

Supplied with current it is a solenoid

Add an iron core – simple form of

ELECTROMAGNET

Page 40: Electricity, magnetism and electromagnetism

What is an electromagnet?

When an electric current is passed through a coil of wire

wrapped around a metal core, a very strong magnetic

field is produced. This is called an electromagnet.

Page 41: Electricity, magnetism and electromagnetism

HOW ELECTRIC & MAGNETIC FIELDS

INTERACT

Faraday discovered that the

magnetic lines of force and the wire

must have a motion relative to each

other to induce an electrical current

Page 42: Electricity, magnetism and electromagnetism

ELECTROMAGNET INDUCTION

Moving a wire through a magnetic field

will induce a current (Faraday)

Wire or field can move

Moving a magnet through a coil of wire

will induce an electrical current

Page 43: Electricity, magnetism and electromagnetism

“FARADAY’S LAWS : OR HOW TO INCREASE THE

STRENGTH OF THE INDUCED CURRENT

Increase the Strength of field or size of

magnet

Increase the SPEED of motion

Change the ANGLE (more

perpendicular)

Increase the Number of Turns of coil

Page 44: Electricity, magnetism and electromagnetism

ELECTROMAGNET INDUCTION

MOVING A BAR

MAGNET THROUGH A

COIL OF WIRE WILL

INDUCE A CURRENT

TO FLOW THROUGH

THAT WIRE

Page 45: Electricity, magnetism and electromagnetism

What are electric motors?An electric motor is a device which changes electrical

energy into mechanical energy.

Page 46: Electricity, magnetism and electromagnetism

How does an electric motor work?

Page 47: Electricity, magnetism and electromagnetism

THE PRINCIPLE OF THE ELECTRIC MOTOR

Page 48: Electricity, magnetism and electromagnetism

GENERATORS

A generator is a device that uses induction to convert mechanical energy into electrical energy.

Page 49: Electricity, magnetism and electromagnetism

TRANSFORMERS

A transformer is a device used to change the

voltage in a circuit. AC currents must be used.

75,000 V in the

power lines

120 V in your

housep = primary

s = secondary

Page 50: Electricity, magnetism and electromagnetism

Transformers are extremely useful because they efficiently change voltage and current, while providing the same total power.

The transformer uses electromagnetic induction, similar to a generator.

Page 51: Electricity, magnetism and electromagnetism