1. JC Technology
Electric Circuits

2. Electric Circuits Computers CD Player IPhone How do they work?
IPhone – Charge battery and turn on
All use Electricity – part of electric circuit
Plug in and turn on

3. Electric Circuits Loop/path/route – connects device to a power supply
Device turned on – electric current flows around the loop
Device works
Simple Circuit
Battery = Power supply
Switch opens & closes circuit

4. Electric Circuits
Circuit Diagrams – symbols are used to represent components =

5. Electric Circuits Electric Current:
The flow of electrons through a conductor
Conductor – materials that allows current to flow through it
examples: copper, gold, silver, tin, iron
Electron – negative charge
Nucleus:
neutrons – no charge
protons – positive charge
Copper Atom

6. Electric Circuits
Electron on outer shell of atoms can move between atoms
No power supply - movement is random
conductor

7. Electric Circuits Conductor connected to power supply:
Electrons all move in same direction – electric current

8. Electric Circuits Measuring electric current – Ammeter
Ammeter must be connected correctly
Unit of measurement = Ampere (A) or amp
Represented by letter I

9. Electric Circuits
Electromotive Force (EMF) – force that makes electrons flow around a circuit
Unit of measurement = Volt
EMF often called Voltage
Higher voltage = more current

10. Electric Circuits Voltage is represented by letter V
Measured using a voltmeter

11. Electric Circuits
Resistance: opposition to the flow of electric current
All components have resistance
Unit of measurement = Ohm (Ω)
Represented by letter R
High resistance = less current

12. Ohm’s Law
‘The electric current in a conductor is directly proportional to the applied voltage and inversely proportional to the resistance at constant temperature’
increasing voltage increases current
increasing resistance decreases current
Ohm’s Triangle

13. Ohm’s Law

14. Series Circuit Components are connected one after the other
Only one path for current to flow around
All components on or off at same time

15. Series Circuit
The current at all points in a series circuit is the same

16. Components of equal resistance – voltage is shared equally
Series Circuit
The applied voltage is shared between the components
Components of equal resistance – voltage is shared equally
B1 = B2

17. Components of unequal resistance – voltage is shared proportionally
Series Circuit
The applied voltage is shared between the components
Components of unequal resistance – voltage is shared proportionally
B1 ≠ LED

18. Series Circuit Voltage across each component depends on its resistance
High resistance = high voltage share
Low resistance = low voltage share

19. Series Circuit
Calculating voltage across each component

20. Parallel Circuit Components are connected side by side
There is more than one path for the current to flow around
Components - on or off at the same or different times

21. Parallel Circuit Current is shared between the parallel paths
Components of equal resistance = equal current
A1 = Current in circuit
A2 = A3
A1 = A2 + A3

22. Parallel Circuit Current is shared between the parallel paths
Components of unequal resistance = unequal current
A1 = Current in circuit
A2 ≠ A3
A1 = A2 + A3

23. Parallel Circuit The voltage across each path = applied voltage
R1 = R2

24. Parallel Circuit The voltage across each path = applied voltage
R1 ≠ R2