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Volts
Energy is measured in Joules.
The power
supply (the cell or battery)
gives an amount of energy to each
Coulomb going
around an electric circuit.
1 Volt = 1 Joule per Coulomb.
The word "per" means "divided
by",
so Voltage = Energy ÷
Charge.
This can be
rearranged to give
Energy = Voltage x
Charge. E = V x
Q.
A 6 Volt
cell gives 6 Joules of energy
to each Coulomb
going around the circuit.
Voltage (which is also called
potential difference, or p.d.)
is measured using a voltmeter.
The voltmeter, shown as a circle with the letter
V inside,
is always connected in parallel with the component.
(The voltmeter is said to be connected
across the component,
where the word "across" means
"in parallel with").
The circuit on the left would show the voltage of the cell.
The circuit on the right
shows the voltmeter connected
across a lamp.
This will tell you how many Joules of
energy are being converted
from electrical energy into
light energy (+heat)
for each Coulomb which passes through
it.
A reading of 6 Volts tells you that 6
Joules of energy
are being converted for each
Coulomb passing through the
lamp.
A reading of 10 Volts tells you that 10
Joules of energy
are being converted for each
Coulomb passing through the
lamp.
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Copyright © 2008 Dr. Colin France. All Rights Reserved.