Transcript 06 What is voltage or potential difference notes

WHAT IS VOLTAGE (OR
POTENTIAL DIFFERENCE)?
A battery has chemical potential energy.
Energy (E) is measured in joules (J).
Chemical reactions in a battery energize and
separate electrons from atoms.
The negative terminal of the battery produces
energized electrons. The positive terminal lacks
electrons.
When the switch on a circuit is closed, the
energized electrons move from the negative
terminal, through a load and return to the
positive terminal with no remaining energy.
The chemical energy from the battery is
converted to light energy in a light bulb.
3. Electrons return
to positive terminal
with no energy left
1. Energized
electrons leave
the negative
terminal
2. Electrons give
up their energy to
the load
Potential difference:
The easiest way to think
about what batteries do is
to use a water analogy.
Batteries ‘lift’ electric
charges to a higher
potential. There is a
potential difference
between one end of a
battery to the other.
The electric charges with
higher potential energy
can now do work, by
flowing ‘downhill’ through
a load.
Potential difference is the difference in potential
energy per coulomb of charge between two
points in the circuit.
Potential difference is also called voltage or
electric potential.
Potential difference is measured in volts by a
voltmeter.
Which of these
figures illustrates
higher potential
difference or voltage?
Variable
Variable
Symbol
Unit
Unit Symbol
Potential
difference or
voltage
V
volts
V
energy
E
joules
J
electric
charge
Q
coulomb
C
NOTE: Potential difference or voltage is the only variable
where the symbol for the units is the same as the
symbol for the variable.