Magnetism Magnets and Magnetic Fields O Magnetic poles

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Magnetism

Magnetism

Magnets and Magnetic Fields O Magnetic poles: one of two points, such as the

Magnets and Magnetic Fields O Magnetic poles: one of two points, such as the ends of a magnet, that have opposing magnetic qualities. O North or south poles O 2 like poles repel each other. 2 unlike poles attract each other. O Some materials can be made into permanent magnets. O Iodestones

Magnets and Magnetic Fields O Magnets exert magnetic forces on each other. O Magnetic

Magnets and Magnetic Fields O Magnets exert magnetic forces on each other. O Magnetic field: a region where a magnetic force can be detected. O Magnets repel or attract each other because of the interaction of their magnetic forces. O Magnets are sources of magnetic fields

Magnets and Magnetic Fields O Magnetic field lines can be used to represent magnetic

Magnets and Magnetic Fields O Magnetic field lines can be used to represent magnetic fields. O Magnetic field lines always form closed loops. O Compasses align with Earth’s magnetic field

Earth’s Magnetic Field O Earth’s magnetic field runs from geographic south to geographic north.

Earth’s Magnetic Field O Earth’s magnetic field runs from geographic south to geographic north. O Magnetic north is different from geographic north. O The source of Earth’s magnetism is not yet fully know.

Magnetism from Electric Current

Magnetism from Electric Current

Electromagnetism O When a wire carries a strong, steady current, all the compass needles

Electromagnetism O When a wire carries a strong, steady current, all the compass needles move to align with the magnetic field created by the electric current. O Solenoids and bar magnets have similar magnetic fields. O Solenoid: a coil of wire with an electric current in it.

Electromagnetism O The strength of a solenoid can be increased. O Electromagnet: a coil

Electromagnetism O The strength of a solenoid can be increased. O Electromagnet: a coil that has a soft iron core and that acts as a magnet when an electric current is in the coil O Moving charge cause magnetism.

Electromagnetic Devise O Electric motor: a device that converts electrical energy into mechanical energy.

Electromagnetic Devise O Electric motor: a device that converts electrical energy into mechanical energy. O A motor can perform mechanical work when it is attached to an external devise. O Galvanometers detects, measures, and determines currents in a circuit much like a voltmeter.

Right Hand Rule O If you hold a wire in your right hand point

Right Hand Rule O If you hold a wire in your right hand point your thumb in the direction of the positive current, the direction that your fingers curl is the direction of the magnetic field. O ** Never grasp or touch an insulated wire connected to a power source.

Electric Currents from Magnetism

Electric Currents from Magnetism

Electromagnetic Induction O Moving a magnet into and out of a coil of wire

Electromagnetic Induction O Moving a magnet into and out of a coil of wire causes charges in the wire to move. O Electromagnetic induction: the process of creating a current in a circuit by changing the magnetic field. O Faraday’s Law: An electric current can be produced in a circuit by changing the magnetic field crossing the circuit.

Electromagnetic Induction O Electromagnetic induction obeys conservation of energy. O The magnetic force acts

Electromagnetic Induction O Electromagnetic induction obeys conservation of energy. O The magnetic force acts on moving electric charges. O Generators convert mechanical energy into electrical energy. O Alternating current (A/C): an electric current that changes direction at regular intervals. O House current O 110 V or 220 V O Direct current (D/C): an electric current that goes in a straight line. O Car current O AA batteries

Electromagnetic Force O Electricity and magnetism are two aspects of a single force, the

Electromagnetic Force O Electricity and magnetism are two aspects of a single force, the electromagnetic force. O EM waves are made up of oscillating electric and magnetic fields that are perpendicular to each other. O EMP

Transformers O Transformer: a device that increases or decreases the voltage or alternating current.

Transformers O Transformer: a device that increases or decreases the voltage or alternating current. O Step-up transformer O Step-down transformer O In its simplest form, a transformer consists of two coils or wire wrapped around opposite sides of a closed iron loop. O Transformers must obey the laws of conservation of energy. O Transformers are used to transfer of electrical energy from high voltage to low voltage or low voltage to high voltage.