P5 - Flashcards in GCSE Physics

Created by: ramsha4
Created on: 11-06-15 14:12

A.C Generators 1

A magnet rotates in a coil of wire. As the magnet turns, the magnetic field changes, inducing a voltage which makes the current flow. When the magnet is turned through a half a turn, the direction of the magnetic field through the coil reverses.

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A. C Generators 2

Then the current flows in the opposite direction around the coil of the wire. If the magnet keeps turning in the same direction then the voltage keeps on reversing every half turn and you get an A.C current.

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Transformers 1

The primary coil produces a magnetic field which stays within the iron core. Because, there's an A.C present, the magnetic field in the iron core constantly changes direction so it is changing magnetic fields.

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Transformers 2

This changing magnetic field induces an alternating voltage in the secondary coil (electromagnetic induction). The relative number of turns on the two coils determines whether the voltage induced in 2nd coil is , than the voltage in the 1st coil.

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Magnetic field 1

A current-carrying wire or coil can exert a force on another current-carrying wire or coil or on a permanent magnet. When a current-carrying wire is put in a different magnetic field, the two magnetic fields affect each other, resulting in a force.

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Magnetic field 2

To feel the full force, the wire has to be at right-angles to the lines of force on the magnetic field its placed in. If a wire runs parallel to the lines of force of the magnetic field, it won't experience a force.

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Electric Motor 1

There are forces acting on the two sides of a coil. These forces act on any current-carrying wire in a magnetic field. Because the coil is on a spindle and the forces act one up and one down, it rotates.

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Electric Motor 2

The split-ring commutator swaps the contacts every half turn. This reverses the direction of the current every half-turn to keep the coil continuously rotating in the same direction. Otherwise, the coil would change direction, not rotate fully.

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A. C Generators 2

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Card 4

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