introduced d.c. voltages. The voltage between two points
in a circuit is referred to as the potential difference and is the work
done (W) in joules, to move
1
coulomb of charge (Q) between these
points.
In general
W (joules)
V (volts) = -
Q (coulombs)
Transposing the formula gives
W
Q = — and W = VQ
V
A voltage produces current in a circuit. The unit of current is the
ampere (A), and the quantity symbol is /. Current is the flow of
electrons, and if a charge of 1 coulomb, which equals 6.241 x 10
18
electrons, passes a given point in 1 second (/) then this constitutes a
current of 1 ampere.
In general
Q (coulombs ...
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