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Electricity and Magnetism Resistors in Series and Parallel If two or more resistors are connected to a battery, the current which will flow through the battery depends on the effective resistance, RE, of all the resistors. We can consider RE to be the single resistor which would take the same amount of current from the same battery. Resistors in Series
In circuit A The current through all the resistors is the same, I. Voltage across R1 is V1 ....................V1 = IR1 similarly, ....................................V2 = IR2 ...........V3 = IR3 Also,........ V1 + V2 + V3 = V In circuit B V = IRE Combining these two gives IRE = IR1 + IR2 + IR3
Resistors in Parallel
In circuit A Voltage across all the resistors is the same, V. The current through R1 is I1 .............I1 = V/R1 similarly, ...............................I2 = V/R2 ..............I3 = V/R3 Also, ...............I1 + I 2 + I 3 = I In circuit B I = V/RE Combining these two gives V/RE = V/R1 + V/R2 + V/R3
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© David Hoult 2008 |
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