# Section 6- Magnetism and Electro-magnetism

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• Section 6- Magnetism and Electro-magnetism
• Magnets and Magnetic Fields
• Magnets produce Fields
• Magnetism can be Induced
• Like poles repel each other
• Opposite Poles attact
• To see the magnetic field, you can get a bar magnet and lay a paper on top and put iron filing on top of it.
• Magnetic Field Line means the path strength of magnet
• Electro-magnetism
• A current- Carrying wire creates a magnetic Field
• There is a magnetic Field around a straight, current- carrying wire
• The magnetic field around a straight wire
• The Motor Effect
• It is a magnet exerting a force on the carry wireing
• This simple device shows that when an electrical current flows through a magnetic field, a force is exerted on the current. This force can be used to make an electric motor.
• Electric Motors and Loudspeakers
• A loudspeaker is a linear motor with a small range. It has a single moving coil that is permanently but flexibly wired
• The coil moves in the field of a permanent magnet, which is usually shaped to produce maximum force on the coil.
• Electric Motors only work on direct current
• This is because current only flows in one direction
• Electromagnetic Induction
• Electromagnetic induction occurs when a circuit with an alternating current flowing through it generates current in another circuit simply by being placed nearby.
• An alternating current is the kind of electricity flowing through power lines and home wiring, as opposed to a direct current, which we get from batteries.
• Faraday's Law. is the right hand rule
• Transformers
• Transformers change the voltage up and down
• They work by combining an oscillating electromagnets with another coil to induce
• Transformers only work on Alternating Current
• If the voltage decreases it is called a step down
• If the voltage increases it is called at step down.
• The ratio of turns= ration of the voltage
• Equation is Input (Primary) Voltage/ Output (secondary) Voltage= Number of turns on primary/ number of turns on secondary