Deriving the Equation for Resistors in Parallel In a parallel circuit, the reciprocal of the combined resistance of two or more resistors is the sum of the reciprocal of the individual resistances ...
Deriving the Equation for Resistors in Series In a series circuit, the combined resistance of two or more resistors is the sum of the individual resistances In a series circuit: The current is the ...
Solving Problems with Kirchhoff's Laws Kirchhoff’s laws can be used to solve simple circuit problems Worked Example For the circuit below, state the readings of ammeters A1, A2 and A3. Worked Exam...
Kirchhoff's Second Law Kirchhoff’s second law states that: The sum of the e.m.f’s in a closed circuit equals the sum of the potential differences This is a consequence of conservation of energy Bel...
Kirchhoff's First Law Kirchhoff’s first law states that: The sum of the currents entering a junction always equal the sum of the currents out of the junction This is a consequence of conservation o...
Internal Resistance All power supplies have some resistance between their terminals This is called internal resistance (r) This internal resistance causes the charge circulating to dissipate some e...
Electromotive Force When charge passes through a power supply such as a battery, it gains electrical energy The electromotive force (e.m.f) is the amount of chemical energy converted to electrical ...
Circuit Symbols The diagrams below show the various circuit symbols that could be used in circuit diagrams. You will be expected to recognise and draw all of these The most common symbols are as fo...
Resistance in a Light-Dependent Resistor A light-dependent resistor (LDR) is a non-ohmic conductor and sensory resistor Its resistance automatically changes depending on the light energy falling on...
