Topic 2 Electricity Within a Circuit
Static and Current Electricity:
When charged particles build up in an object it is called static electricity.
Another kind of electricity occurs when electrons flow in a current. • A battery and wires can make current flow
What is an electric current?
An electric current is the flow electrons flowing
through wires and components.
+ -
In which direction does the current flow? from the Negative terminal to the Positive terminal of a cell.
Current Electricity
•As electrons pass through the wire and into the light bulb, the filament lights the bulb
simple circuits
simple electric circuit: It has a cell, a lamp and a
switch.
Circuit: components are connected together with
metal wires
cell
lamp
switch
wires
simple circuitsWhen the switch is closed, the lamp lights up. This
is because there is a continuous path of metal for the electric current to flow around.
If there were any breaks in the circuit, the current could not flow.
circuit diagram:
cell switch
lamp
wires
Scientists usually draw electric circuits using symbols;
circuit diagramsIn circuit diagrams components are represented
by the following symbols;
cell battery
switch
lamp
motorammeter
voltmeter
buzzer
resistor
variable resistor
measuring current
Electric current is measured in amps (A) using
an ammeter connected in series in the circuit.
A
measuring current
A A
This is how we draw an ammeter in a circuit.
SERIES CIRCUIT PARALLEL CIRCUIT
Lets give electrical diagrams a whirl…
DRAW THISELECTRICAL
CIRCUIT
DRAW THISELECTRICAL
CIRCUIT
Consider this to be a Switch
Label the circuit components
A
Label the circuit components
A
Haha, just kidding
measuring voltageThe ‘electrical push’ which the cell gives to the
current is called the voltage. It is measured in
volts (V) on a voltmeter. It provides the energy
for the moving electrons.
Voltage is also referred to as “Potential
Difference”
V
Different cells produce different voltages. The
bigger the voltage supplied by the cell, the bigger
the current.
measuring voltage
Unlike an ammeter a voltmeter is connected
across the components
Scientist usually use the term Potential
Difference (pd) when they talk about voltage.
Thinking of Electricity like Water
Current is literally just the amount of water flowing through a channel. - This is analogous to electricity flowing through a wire
Less water means less water molecules
are flowing
More water means more water molecules are
flowing
Amps (or amperes) measures current – the amount of electricity flowing through some point.
Amperes are measured in coulombs per second.
Just like measuring amps of
electricity, you could set up a flow meter to
measure exactly how much water is flowing past
this point
Volts• Voltage is analogous to water pressure • Voltage is the force that moves the electrons through the wire. Increasing
voltage increases current (electron) flow
water which falls from a high
waterfall has more pressure
than water which falls over the edge
of small rocks
9V 1.5V
WattsWatts = A measure of power / the rate of energy consumed by an electrical device when it is operating
Watts are calculated by multiplying the voltage at which an appliance operates (i.e. 1.5 V) by the current it draws
