This document defines and describes electric fields, electric current, and electrical circuits. It discusses how electric fields create forces on charged particles, how current is the flow of electric charge in a circuit, and how circuits can be connected in series or parallel. Components like batteries, bulbs, switches, and wires are explained. Diagrams illustrate key concepts like open versus closed circuits, series versus parallel connections, and circuit symbols.

1. Electric Field, Electric Current
and Electrical Circuit

2. Electric Field
• is a region in which an electric charge
experiences a force.
• it is represented by lines that indicate the
direction of force.
+
Away from the
positive charge
-
Towards the
negative charge

3. Two similar charges repel each
other

4. Closer field lines indicate a
stronger electric field.
Field lines that are further
apart indicate a weaker
electric field.
Two opposite charges
attract each other.

5. Effect of an Electric Field
+
++
+
--
--
-
+
+
+
+
+
+
+
+
+
-
-
-
-
-
-
-
-
-
+ -
The flame is spread out more to
the negative plate as the
positive charges are heavier
than the negative charges.
+
+
+

6. +
-
Air Molecule
Ionisation
Heat energy from flame
+
-
Positive
Charge
Negative
Charge
Negative Plate
Positive Charge

7. Electric Current
connecting
wire
electric
cell
filament
flow of electrons
Conductor
Charge
Cross-sectional area
Definition:
An electric current is
the rate of flow of
electric charges in a
circuit.

8. How does electricity flow?
• The battery in a circuit gives energy to the
electrons and pushes them around a circuit,
from the negative terminal of the cell, round
the circuit and back to the positive terminal
of the cell.

9. • The SI unit for electric current is ampere (A).
• Smaller currents are measured in milliamperes
(mA).
• Different electrical components and appliances
require different sizes of current to turn them on.
How to Measure Current?
1 A = 1,000 mA
1 mA = 0.001 A

10. Instrument to Measure Current
• An ammeter is an instrument used for
measuring electric current.

11. Ammeter
• It must be connected in series in the circuit.
• Positive side of ammeter must be connected
nearest to the positive terminal of the battery
(electric cell), and vice versa.

12. Electric Circuits
• Electric circuits are
made up of electrical
components
• These components
must be joined together
without any gap in
between to form a
closed circuit.
connecting wires
electric cell
circuit boardlight bulb
Note:
Components refer to the
light bulb, wires, battery

13. Electric Circuits
• Incomplete circuits are called open circuits.
connecting wire is
missing
no source of
electrical energy
Both the circuits in the diagram are incomplete, hence they are known as
“open circuits”.

14. An electric current flows only
when there is:
• a source of electrical energy and
• a closed circuit
connecting wires
electric cell
circuit boardlight bulb

15. How to draw Circuit Diagrams
Component Symbol Component Symbol
An electric cell Battery
Light bulb (lamp) Switch
Switch (open)
Switch (closed)
Connecting wires
(not joined)
Connecting wires
(joined)
+ +
Symbols are used to represent the various electrical components
in circuits.

18. Can you predict how this circuit would looked
like in its schematic format?

19. Switches
A switch is used to open or close a circuit.
Main switch
used in
buildings
Switches used on circuit boards

20. Series and Parallel
There are 2 ways inwhichan electric circuit can
be arranged:
1. Series
2. Parallel

21. Series Circuit
• A series circuit connects the components one after
the other
• A single loop is formed
• A break in any part of a series circuit stops the flow
of current in the whole circuit.

22. Parallel Circuit
• A parallel circuit divides into two or more branches.
• The current divides and flows through each parallel
branch.
• If a component breaks or is removed, the other
components remain on.

23. Which of the following is a
series circuit?
Which is a parallel circuit?
SeriesCircuit ParallelCircuit

24. Draw the circuit diagram for the
following set up and state whether it
is a series or parallel circuit.

25. Draw the circuit diagram for the
following set up and state whether it is a
series or parallel circuit.

26. Which is brighter?

27. Which of the following is a series
circuit?
Which is a parallel circuit?
Series Circuit Parallel Circuit