Friday, February 24, 2012

recent notes

Voltage (V) = available energy per coulomb of charge

V = E/q

units are volts (V)


Current (I) = rate at which charge travels in a circuit

I = q/t

units are amperes or amps (A)


Resistance (R) = the ratio of applied voltage to the current through the "resistor"

R = V/I

units are ohms (omega symbol)

The relationship that governs all three is the last expression above, often called Ohm's law and expressed typically as:

V = I R

In short:

Voltage is an energy per charge - sort of like the total energy the battery has, but measured as a ratio of energy per coulomb of charge

Current is how "fast" charge travels, but in coulombs per second (amps)

Resistance is how much the resistor "resists", in terms of a ratio: V/I

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