2What is a magnetic field? Where would you find a magnetic field?
3strongest field at poles Magnetic fieldAround every magnet is an invisible force field that will affect all magnetic objects inside it.The magnetic field of a bar magnet is seen with iron filings.strongest field at polesNSWhat does the magnetic field around a bar magnet look like?Where is the magnetic field strongest?
4What materials will stick to magnets? Look around the laboratory or your teacher will provide a tray.See which materials will stick to a magnet and which materials will not.Magnetic materialsNon-magnetic materials
5What materials will magnets stick to? Magnets and materialsWhat materials are magnets made from?Iron or steel.NSWhat materials will magnets stick to?Iron or steel.And nickel!
7Repulsion and attraction Repel/attractRepel/attractRepel/attractUnlike poles attract.Like poles repel.
8Separating coinsHow could you separate steel and gold coins using a magnet?NSSteel coins would stick to magnet, gold coins would be left behind.
9What does the magnetic field for a bar magnet look like? In what direction do magnetic field lines point?N North to South S
10Revising magnetism I Iron or steel Magnets are made from which materials? ___________The PolesWhat are the ends of a magnet called? __________What do we call the area around a magnet where amagnetic force exists? __________________The Magnetic FieldPull togetherWhat does the word attract mean? __________What does the word repel mean? __________Push apart
11Revising magnetism II Repel What will two north poles do if brought together? _____RepelWhat will two south poles do if brought together? ______RepelWhat will a north and a south pole do if broughttogether? _______AttractIron and steelWhat materials are attracted by magnets? ___________Is magnetism a contact or non-contact force? _________Non-contact
12ElectromagnetsA coil of wire acts like a bar magnet when it has an electric current flowing through it.One end of the coil becomes a north-seeking pole.One end of the coil becomes a south seeking pole.This is called an electromagnet.
13Making an electromagnet: Apparatus:BatteriesWireIron NailWhat to do:Wrap a coil of wire around the iron nail.Connect the coil of wire to the batteries.See how many paperclips you can pick up.
14Results How many paperclips could you pick up? Can you think of any ways to make the electromagnetpick up more paperclips?More batteries (more current)Number of paperclipsNumber of batteriesMore turns of wire on the coilNumber of paperclipsNumber of turns
16Electromagnetic strength - results The results for the number of drawing pins attracted to the electromagnet with no core are:1234681218numberof cellsnumberof coilsHow does changing the current affect the strength of an electromagnet?How does changing the number of coils affect the strength of an electromagnet?
17Electromagnetic strength - results Compare the results for the number of drawing pins attracted to the electromagnet with no core and an iron core:1234681218numberof cells12346810121622numberof cellsnumberof coilsnumberof coilsWhat effect does an iron core have on the strength of an electromagnet?
18Electromagnetic strength - results Compare the results for the number of drawing pins attracted to the electromagnet with no core and a copper core:1234681218numberof cells1234681218numberof cellsnumberof coilsnumberof coilsWhat effect does a copper core have on the strength of an electromagnet?
19Ways to make an electromagnet stronger There are three ways to make an electromagnet stronger. Do you know them?___________________More turns on the coilMore electrical currentUsing an iron coreSSNWhat happens if you turn the battery around in an electromagnet?The poles on the coil reverse, north becomes south and south becomes north.
20 Attract and repel Attract Repel Stick together What do like poles do?Attract and repelAttractRepelStick together
21Which material below will not stick to a magnet? Steel paper clipAluminium canIron nailSteel key
22Which of the below will not increase the strength of an electromagnet? More coilsMore currentLess currentIron core
23In which direction do magnetic field lines always point? East to westWest to eastSouth to northNorth to south
24Which of the following is not a use of electromagnets? Fridge magnetsLoud speakersRelaysCircuit breakers