Download Electricity notes - Lesmahagow High School

ELECTRICITY
Summary Notes
1.REVISION OF PS ELECTRICITY (A)

When drawing components in an electric circuit,
SYMBOLS are used
component
symbol
energy change
wire
none
cell
chemical to electrical
battery
chemical to electrical
switch
none
buzzer
electrical to sound
lamp
electrical to light
motor
M
electrical to movement
2.REVISION OF PS ELECTRICITY (B)

In a series circuit components are connected one
after another with no branching:

Examples of series circuits include:
Christmas tree lights
 Switches and fuses


Electric current WILL pass through a conductor
and will NOT pass though an insulator.
3. SIMPLE CAR CIRCUITS
In a parallel circuit components are
connected “side-by-side” so that
the circuit branches.
 Examples of parallel circuits
include:
 House circuits
 Car circuits

4. MEASURING ELECTRIC CURRENT (A)
An ammeter is used to measure current in units of
amps (A).
 An ammeter is always connected in series

2A
2A

2A
2A
A
The current is the same at every point in a series
circuit.
4. MEASURING ELECTRIC CURRENT (B)

The currents in the
branches of a parallel
circuit add up to the
current from the
source.
3A
3A
1A
1A
1A
5. MEASURING ELECTRIC VOLTAGE (A)

A voltmeter is used to
measure voltage in units
of volts (V).

A voltmeter is always
connected in parallel.
V
5. MEASURING ELECTRIC VOLTAGE (B)

The voltage across each branch in a parallel
circuit is equal to the voltage across the battery.
3V
3V
3V
3V
5. MEASURING ELECTRIC VOLTAGE (C)

The voltages across each component in a
series circuit add up to the voltage across the
battery.
3V
1.5V
1.5V
6. ELECTRICAL RESISTANCE
Circuit components resist current.
 The greater the resistance the smaller the current.
 A thin wire has more resistance than thick wire.
 A long wire has a greater resistance than short
wire

7. STAYING SAFE WITH ELECTRICITY
Passing a current in a wire causes it to heat up.
 If the current in a wire gets too high,

fuses are used to protect the wire.
 the fuse melts and breaks the circuit.
 this stops the current and keeps the wire safe.
