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© Boardworks Ltd 2004 1 of 20 © Boardworks Ltd 2005 1 of 26 KS4 Physics Electromagnetism.

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Presentation on theme: "© Boardworks Ltd 2004 1 of 20 © Boardworks Ltd 2005 1 of 26 KS4 Physics Electromagnetism."— Presentation transcript:

1 © Boardworks Ltd of 20 © Boardworks Ltd of 26 KS4 Physics Electromagnetism

2 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Electromagnetism Magnets Magnetic fields Summary activities Electromagnets Contents

3 © Boardworks Ltd of 20 © Boardworks Ltd of 26 A magnetic material is attracted to magnets and can be made into a magnet. Magnetic materials Non-magnetic materials Which materials are attracted to a magnet? iron, steel, cobalt and nickel Magnetic or non-magnetic? N S Investigate different materials to find out which are attracted to a magnet and record your results in a table.

4 © Boardworks Ltd of 20 © Boardworks Ltd of 26 How can a magnet be used to separate coins made from steel and coils made from gold? Steel coins are attracted to a magnet but gold coins are not. Using magnets to separate coins N S

5 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Steel is harder to magnetise but does not lose its magnetism easily. Steel is called a What materials can magnets be made from? iron, steel, cobalt and nickel N S Magnetic materials Iron is easy to magnetise and also loses its magnetism easily. Iron is called a Magnets are usually made of steel and other hard magnetic materials because they can retain their magnetism. soft magnetic material. hard magnetic material.

6 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Electromagnetism Magnets Magnetic fields Summary activities Electromagnets Contents

7 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Where would you find a magnetic field? What is a magnetic field?

8 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Around 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. N S What does the magnetic field around a bar magnet look like? strongest field at poles Where is the magnetic field strongest? Magnetic field of a bar magnet

9 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Forces between magnets – experiment

10 © Boardworks Ltd of 20 © Boardworks Ltd of 26 repel/attract Unlike poles attract. Like poles repel. Repulsion and attraction N S S N S N N S S N S N

11 © Boardworks Ltd of 20 © Boardworks Ltd of Magnets are made from which materials? ____________ 2. What are the ends of a magnet called? ________ 3. What do we call the area around a magnet where a magnetic force exists? _______________ 4. What does the word attract mean?_____________ 5. What does the word repel mean?_____________ iron or steel poles magnetic field pull together push apart Revising magnetism (1)

12 © Boardworks Ltd of 20 © Boardworks Ltd of What will two north poles do if brought together? ______ 7. What will two south poles do if brought together? ______ 8. What will a north pole and a south pole do if brought together? _______ 9. What materials are attracted by magnets? _____________ 10. Is magnetism a contact or non-contact force? ___________ repel attract iron and steel non-contact Revising magnetism (2)

13 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Electromagnetism Magnets Magnetic fields Summary activities Electromagnets Contents

14 © Boardworks Ltd of 20 © Boardworks Ltd of 26 A 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 (N pole). One end of the coil becomes a south seeking pole (S pole). What is an electromagnet? This is called an electromagnet.

15 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Apparatus: batteries wire iron nail What to do: 1.Wrap a coil of wire around the iron nail. 2.Connect the coil of wire to the batteries. 3.See how many paperclips the electromagnet can pick up. Results: How many paperclips could the electromagnet pick up? How could the electromagnet pick up more paperclips? Making an electromagnet

16 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Investigating electromagnets – experiment

17 © Boardworks Ltd of 20 © Boardworks Ltd of 26 The results for the number of drawing pins attracted to the electromagnet with no core are: number of cells number of coils How does changing the current affect the strength of an electromagnet? How does changing the number of coils affect the strength of an electromagnet? Investigating electromagnets – results (1)

18 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Number of paperclips Current (amps) x x x x x x x Increasing the number of cells, increases the current, and the number of paperclips picked up by the electromagnet also increases. The strength of the magnetic field increases as the current flowing through the coil increases. Effect of increasing the current x

19 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Number of paperclips Number of turns x x x x x x x Increasing the number of turns on the coil, increases the number of paperclips picked up by the electromagnet. The strength of the magnetic field increases as the number of turns on the coil increases. Effect of increasing the number of coils x

20 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Compare the results for the number of drawing pins attracted to the electromagnet with no core and an iron core: number of cells number of coils number of cells number of coils What effect does an iron core have on the strength of an electromagnet? Investigating electromagnets– results (2)

21 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Compare the results for the number of drawing pins attracted to the electromagnet with no core and a copper core: number of cells number of coils number of cells number of coils What effect does a copper core have on the strength of an electromagnet? Investigating electromagnets – results (3)

22 © Boardworks Ltd of 20 © Boardworks Ltd of 26 There are three ways to make an electromagnet stronger. What are they? 1.____________________ 2.____________________ 3.____________________ More turns on the coil More electrical current Using an iron core S N What happens if the position of the battery in the electromagnet circuit is reversed? The poles on the coil also reverse – north becomes south and south becomes north. Electromagnets – summary N S

23 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Electromagnetism Magnets Magnetic fields Summary activities Electromagnets Contents

24 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Glossary core – An object, usually made of iron, which is placed inside the coil of an electromagnet and increases the strength of the magnetic field. electromagnet – A coil of wire that produces a magnetic field when a current is passed through it. hard magnetic material – A material that is hard to magnetise but does not lose its magnetism easily. magnetic field – The invisible force field around a magnet or electromagnet that will affect all magnetic objects within that area. poles – The parts of a magnet where the magnetic field is strongest. soft magnetic material – A material that is easy to magnetise and also loses its magnetism easily.

25 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Anagrams

26 © Boardworks Ltd of 20 © Boardworks Ltd of 26 Multiple-choice quiz


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