# GCSE

## Electricity in the Home

– Direct Current – D.C. is current that travels in one direction only, e.g. from a battery. On a Cathode Ray Oscilloscope, D.C. looks like:   Alternating Current – A.C. is current that constantly changes direction, e.g. from mains electricity (50Hz, 240V). On a...

## Electromagnetic Induction

Electromagnetic induction is when an electromotive force (emf) is induced in a conductor when lines of flux are being cut. This can occur when a magnet is moved relative to a coil of wire. This is the basis of A.C. generators and transformers.  Transformers use a...

## Resistance and Ohm’s Law

– Resistance is the opposition to the flow of current. Resistance x Current = Voltage, or:   For resistors in parallel, the reciprocal of the total resistance is equal to the sum of the reciprocals of the individual resistances: If two equal resistors are in...

## Electric Circuits

Standard symbols for circuit diagrams are as follows:   Every cell has a positive and negative terminal. The polarity of a cell refers to the physical alignment of the cells in respect to their terminals (i.e. the direction they are facing). The voltage...

## Waves

Waves transfer energy from one place to another through vibrations. The wavelength of a wave is the distance between two successive crests (length). The amplitude of a wave is the maximum displacement of a particle in the wave from its equilibrium position (length)....