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1. Circuits Electrical Components and Symbols Series Circuits Parallel Circuits Measuring Current (Amps) Current Flow and Charge Current in Series vs Parallel Conductors and Insulators Energy Transfer in Circuits
Year 8 • Physics
Circuits
This lesson explains how electrical circuits work, the symbols used for components, differences between series and parallel circuits, how current flows, and how energy is transferred in everyday electrical devices.
Lesson Objectives
- Identify electrical components and symbols.
- Describe series and parallel circuits.
- Measure current correctly in a circuit.
- Understand how current and charge flow.
- Explain energy transfer in circuits.
1. Electrical Components and Symbols
Electrical circuits are made using components.
To make circuit diagrams clear and universal, we use symbols.
[ Image Placeholder – Electrical Components & Symbols Diagram ]
Common components:
• Cell / battery – provides energy
• Bulb – gives light
• Switch – opens or closes the circuit
• Wire – connects components
• Ammeter – measures current
• Cell / battery – provides energy
• Bulb – gives light
• Switch – opens or closes the circuit
• Wire – connects components
• Ammeter – measures current
2. What Is an Electric Circuit?
An electric circuit is a complete loop that allows current to flow.
If the circuit is broken (open), current cannot flow.
If the circuit is complete (closed), current flows.
If the circuit is complete (closed), current flows.
Real-life connection:
A torch only works when the circuit inside is complete.
3. Series Circuits
In a series circuit, components are connected in a single loop.
[ Image Placeholder – Series Circuit Diagram ]
Key points:
• Same current flows everywhere
• If one component breaks, all stop working
• Bulbs become dimmer as more are added
• Same current flows everywhere
• If one component breaks, all stop working
• Bulbs become dimmer as more are added
4. Parallel Circuits
In a parallel circuit, components are connected on separate branches.
[ Image Placeholder – Parallel Circuit Diagram ]
Key points:
• Current splits between branches
• If one bulb breaks, others still work
• Used in homes and buildings
• Current splits between branches
• If one bulb breaks, others still work
• Used in homes and buildings
5. Measuring Current (Amps)
Current is the flow of electric charge.
[ Image Placeholder – Ammeter Connected in Series ]
• Measured using an ammeter
• Unit: ampere (A)
• Ammeter is always connected in series
• Unit: ampere (A)
• Ammeter is always connected in series
6. Current Flow and Charge
Electric current is the flow of electric charge through a circuit.
• Charge flows from the battery through components
• Current is the same at all points in a series circuit
• Current splits in parallel circuits
• Current is the same at all points in a series circuit
• Current splits in parallel circuits
Think of current like water flowing through pipes.
7. Conductors and Insulators
Materials affect how easily current flows.
Conductors: metals like copper, aluminium
Insulators: plastic, rubber, wood
Insulators: plastic, rubber, wood
Real-life example:
Wires have metal cores with plastic insulation to protect us.
8. Energy Transfer in Circuits
Electrical energy is transferred into other forms.
• Bulb: electrical → light + heat
• Motor: electrical → movement
• Heater: electrical → heat
• Motor: electrical → movement
• Heater: electrical → heat
Practice Questions
A. Fill in the Blanks
- An ammeter measures __________.
- Current is measured in __________.
- A series circuit has __________ loop.
- Plastic is an __________.
- Electrical energy can change into __________ energy.
B. True or False
- Current splits in a series circuit.
- Ammeter is connected in series.
- Homes use parallel circuits.
- Metals are good insulators.
- A broken bulb stops all bulbs in a series circuit.
C. Short Answer
- What is an electric circuit?
- Why are homes wired in parallel?
- Name two conductors.
- What does a switch do?
- What energy change happens in a motor?
D. Thinking Questions
- Why does a torch stop working when one bulb breaks?
- Why are wires coated in plastic?
- Why do bulbs glow dimmer in series circuits?
- Why is an ammeter not connected in parallel?
- Why do devices get warm when used?
✅ Show Answer Key
A. Fill in the Blanks
- current
- amperes
- one
- insulator
- light / heat
B. True or False
- False
- True
- True
- False
- True
C. Short Answer
- A complete loop that allows current to flow.
- So devices work independently.
- Copper, aluminium.
- Opens or closes the circuit.
- Electrical to kinetic energy.
D. Thinking Questions
- The circuit is broken.
- For safety and insulation.
- Current is shared.
- It would change current flow.
- Energy is transferred as heat.
© Aviate Learning – Circuits (Year 8)
🔌 Series vs Parallel Circuit Simulator
Toggle between series and parallel circuits and switch bulbs ON/OFF to see how
current flow and brightness change.
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Series circuit: Current is shared, bulbs are dimmer, one break stops all.