# DATE: TOPIC: ELECTRICITY AND MAGNETISM OBJECTIVE: To establish how electric charges and magnets work.

## Presentation on theme: "DATE: TOPIC: ELECTRICITY AND MAGNETISM OBJECTIVE: To establish how electric charges and magnets work."— Presentation transcript:

DATE: TOPIC: ELECTRICITY AND MAGNETISM OBJECTIVE: To establish how electric charges and magnets work

What is electricity? Electricity is the flow of energy or current through a metallic substance.

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. Magnets produce magnetic forces and have magnetic field lines

OPTIONS contact repel charge Attractive or repulsive distance Attract Electric field induction

OPTIONS Magnetic fields Like magnetic poles Poles On other electric charges Unlike magnetic poles

Electricity and Magnetism – how are they related? When an electric current passes through a wire a magnetic field is formed.

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.

Magnets have two ends or poles, called north and south poles. At the poles of a magnet, the magnetic field lines are closer together. Unlike poles of magnets attract each other and like poles of magnets repel.

Fig. 6.2 Ben Franklin discovered electric charge.

6-12. Magnets Every magnet has a north pole and a south pole.

Fig. 6.39 The experimental Japanese Maglev train uses magnetic forces for both support and propulsion.

Fig. 6.44 Sharks navigate with the help of the earth’s magnetic field. They detect the field using electromagnetic induction.

What are electric circuits ? Circuits typically contain a voltage source, a wire conductor, and one or more devices which use the electrical energy. What is a series circuit? A series circuit is one which provides a single pathway for the current to flow. If the circuit breaks, all devices using the circuit will fail.

What is a parallel circuit? A parallel circuit has multiple pathways for the current to flow. If the circuit is broken the current may pass through other pathways and other devices will continue to work.

What is the difference between an open circuit and a closed circuit ? A closed circuit is one in which the pathway of the electrical current is complete and unbroken. An open circuit is one in which the pathway of the electrical current is broken. A switch is a device in the circuit in which the circuit can be closed (turned on) or open (turned off).

ELECTRIC CHARGES 1. Interact through an Electric field 2. They can be attractive or repulsive 3. Like charges repel 4. Unlike charges attract 5. Force depends on distance 6. Force depends on charge 7. Objects become charged by induction 8. Objects become charged by contact MAGNETS 1. Have 2 poles 2. they are surrounded by magnetic fields 3. These attract unlike magnetic poles 4. These repel like magnetic poles 5. Magnets exert forces on other electric charges

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