Transcript SNC1D1 Potential Difference

10.3 Electric Potential
Electric Potential
• Electric potential refers to the amount of
energy that electrons possess in a circuit.
Electric Potential
Each electron has electric potential
energy.
•Potential energy is the energy stored
in an object.
– example: An apple hanging from a low branch. The
apple has potential energy because of its position above
the ground. If the apple falls down, it will convert its
stored energy, or potential energy, into motion. Suppose
an apple is at a higher branch. It would have even more
potential energy to convert.
Electric Potential
• A load (ex. light bulb) converts electrical energy into another form of
energy (ex. light energy and heat energy).
• You can compare this to the water flowing past a water wheel. The
wheel converts some of the energy of the water into motion. The water
has more energy before the wheel than after the wheel.
• Therefore, there is higher voltage before the load than after the load.
Potential Difference (Voltage)
A battery has chemical potential energy in the
electrolyte in its electrochemical cells.
• The chemicals in the electrolyte react with the
electrodes.
• This causes a
difference in the
amount of electrons
between the two
terminals.
Potential Difference (Voltage)
– One terminal in a battery has
mainly negative charges (electrons).
– The other terminal has mainly
positive charges.
• The negative charges (electrons),
which can move, are attracted to the
positive charges at the positive
terminal.
Potential Difference (Voltage)
• If a conductor, such as a copper wire, is connected
to both terminals, then the electrons flow from the
negative terminal to the positive terminal.
• The difference in electric
potential energy between
two points in a circuit is
called the potential difference
or voltage (V).
Potential Difference (Voltage)
• This difference causes current to flow in a closed
circuit. The higher the potential difference in a
circuit, the greater the potential energy of each
electron.
Measuring Potential Difference
• The potential difference
between two locations in
a circuit is measured with
a voltmeter.
Measuring Potential Difference
• Example: Connecting wires from a negative
terminal on a battery across a voltmeter and
then back to the positive terminal. The
voltmeter would then display the potential
difference of the battery.
• The SI unit for potential difference is the
volt (V).
Measuring Potential Difference
• A voltmeter must be connected in parallel with
a load in the circuit in order to compare the
potential before and after the load.
Measuring Voltage Activity
• Fill in the following table as you follow
the steps below
Connection of
Voltmeter
Potential Difference (V)
Across the battery
Across the light bulb




Construct a circuit using a battery, light bulb, switch, and wires
Connect the voltmeter across the battery
Close the switch and note the potential difference in the table
Repeat the previous three steps after changing the position of the
voltmeter, as described in the table
Homework
• Read pg. 302 - 303
• Answer # 1 - 4, 6 on pg. 303