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BMAT PHYSICS KNOWLEDGE
Static electricity
Insulating materials
Metals are good conductors , which means that electric charges move easily through them.
Materials such as plastic, wood, glass and polythene are insulators. This means they
do not allow electric charges to move through them. Some insulators can become electrically
charged when…

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An atom
When an acetate rod is rubbed with a duster, electrons are transferred from the rod onto the
duster, making the rod positively charged.

Problems with static
Static is a nuisance when:
Dust and dirt is attracted to insulators such as TV screens and computer monitors.
Clothes made from…

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Electric current
Electric current is a flow of electric charge. No current can flow if the circuit is broken - for
example, when a switch is open.

Measuring current
Current is measured in amperes (which is often abbreviated to a
mpsor A ). The current
flowing through a component in…

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Calculating potential difference
The potential difference between two points in an electric circuit is the work done when a
coulomb of charge passes between the points. You can calculate the size of a potential
difference using this equation:
V=W÷Q
V is the potential difference in volts, V
W is the…

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Potential difference
When two or more components are connected in series, the total potential difference of the
supply is shared between them. This means that if you add together the voltages across each
component connected in series, the total equals the voltage of the power supply.

Circuit symbols
You need…

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Series and parallel connections
You should know the difference between series and parallel connections in circuits.

Series connections
Components that are connected one after another on the same loop of the circuit are
connected in series. The currentthat flows across each component connected in series is the
same.
Two lamps…

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The National Grid
Electricity is transferred from power stations to consumers through the wires and cables of
the National Grid. When a current flows through a wire some energy is lost as heat. The
higher the current, the more heat is lost. To reduce these losses, the National Grid
transmits…

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The coil to which the alternating voltage is supplied is called the primary coil or
primary winding. When an alternating potential difference is supplied the resulting
alternating current in the primary coil produces a changing magnetic field around it.
This changing field induces an alternating current in the secondary coil.…

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Stepdown Transformer
A step down transformer has less turns on the secondary coil that the primary coil.
The induced voltage across the secondary coil is less the applied voltage across the
primary coil or in other words the voltage is "steppeddown".



Transformers are very efficient. If it is assumed that…

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The magnetic field is strongest at its poles. The field around a magnet can be
represented by lines with arrows on them. The arrows show the direction of the lines
of force. Each field line starts at the North Pole and finishes at the South Pole.

Magnets affect a wire…

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