Ch 7.4 Magnets and electric fields page 273

YR 7 CH 7 FORCES WIKI

LIQUID FERRO MAGNETS - YOUTUBE 3 MINS

ELECTRO-MAGNET – YOUTUBE 1MIN

Don’t copy

Magnetic Fields Page 274

Magnetic Field Region around a magnet in which a magnetic force is experienced

Poles Ends of a magnet, may be a north or a south pole

P 275

P 275

The Earth’s magnetic field

The Earth’s magnetic field protects us from harmful solar radiation – evidence of this are the Aurora Borealis (northern lights) and Aurora Australis (southern lights).

Aurora – dawn/sunrise Boreas – God the northwind Auster - Southern

Attraction and Repulsion of poles page 276

Magnetic domains page 276

Domains Small regions inside a magnet which each behave as a mini-magnet, with a north and south pole

Types of Magnets page 276

Electro magnets – caused by the floor of electricity in a metal.

Temporary Magnet a magnet made from a material that easily loses its magnetism – eg stroking an iron nail with a permanent magnet.

Permanent Magnet A material that remains magnetic for a long period of time – can be formed by heating or hitting a metal to arrange its domains effectively.

The magnetic strip on your credit card can be damaged by powerful magnets.

Dropping a magnet may disturb its domains – destroying its magnetism.

Electric Fields page 277

Electric Field - Region around a charged object in which another will experience a force

Atoms Tiny particles that make up all matter

Charging up page 277

Insulator - Substance through which electrons do not flow, such a plastic

Conductor - Substance through which electrons can flow, such as metal

Positively charged - has more protons (+) than electrons (-)

Negatively Charged Having more negative charges (electrons) than positive charges (protons)

Static electricity - a tiny imbalance between positive and negative charge on an object

Electrostatic Force Force experienced inside an electric field (also called electric force)

Page 278

Van de Graaff generator

Electric charge discharge page 278

Lightning safety rules page 279

If outside, seek refuge in a car or grounded building when lightning or thunder begins.

If inside, avoid taking baths, or showers, and washing dishes. Also avoid using landline phones, televisions, and other appliances that conduct electricity.

Stay inside for 30 minutes after you last see lightning or hear thunder. People have been struck by lightning from storms centered as far as 10 miles (16 kilometers) away.

If caught outside away from a building or car, stay clear of water bodies and tall objects like trees.

Find a low spot or depression and crouch down as low as possible, but don't lie down on the ground. Lightning can move in and along the ground surface, and many victims are struck not by bolts but by this current.