– 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 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 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...
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 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)....
Insulating materials (like plastic) can be charged by friction due to the transfer of electrons. E.g. When Polythene is rubbed with a cloth, electrons transfer from the cloth to the polythene, resulting in a surplus of electrons on the polythene and an overall...
Our solar system consists of the Sun, 8 planets (the first four are rocky, the other four are gaseous), asteroids and comets. Gravity provides the centripetal force necessary for the orbital motion of the planets, comets, moons and artificial satellites. Two theories...