Different circuits and circuit diagrams
This Topic is About...
- I will learn to use conventional symbols to draw circuit diagrams.
- I will choose components to make and compare circuits with batteries, switches, and buzzers.
- I will compare how bright lamps are in series and parallel circuits.
- I will make predictions about electricity and test them to see if they are correct.
- I will describe risks and learn how to work safely in practical activities.
- I will decide when to repeat observations to make results more reliable.
- I will present and interpret my results in tables.
- I will make conclusions using my understanding of electricity.
- I will identify and classify circuits as series or parallel.
You’re going to become an electricity expert!
Key Words
- circuit diagram
- conventional symbol
- parallel circuit
- series circuit
- symbol
- volt
- voltage
Tap to Learn the Meanings!
- circuit diagram: A picture that shows how electrical parts are connected in a circuit.
- conventional symbol: A simple drawing used to show parts like batteries or lamps in a circuit.
- parallel circuit: A circuit with more than one path for electricity to flow.
- series circuit: A circuit with only one path for electricity to flow through all parts.
- symbol: A small picture that represents an electrical component.
- volt: The unit used to measure electrical energy or voltage.
- voltage: The push that makes electricity move in a circuit.
Fantastic work learning your electricity keywords!
Understanding Circuit Diagrams ⚡
It takes a long time to draw a full circuit showing every battery, lamp, and switch. To make it easier, scientists and engineers use special signs called symbols. A picture that shows how components are connected using these symbols is called a circuit diagram.
What Are Conventional Symbols? 🔌
Everyone around the world uses the same circuit symbols, so we can all understand each other’s diagrams. These are called conventional symbols. Instead of drawing full pictures of components, we use simple shapes to show each part clearly. For example, there are standard symbols for a battery, switch, bulb, motor, and connecting wires.
Reading Circuit Symbols 🧩
Here is a list of circuit components and their symbols. The long lines and short thick lines in cells or batteries show the positive and negative ends. When you look at a circuit diagram, these symbols help you quickly see how electricity flows through the circuit and where each part is connected.
Adding Different Components to a Circuit ⚡
Different components need different strengths of electricity. You can put a buzzer in a circuit instead of a lamp, but the buzzer needs a stronger supply of electricity than the lamp.
What Are Volts and Voltage? ⚙️
The strength of electricity is measured in units called volts (V). The strength that a component needs for it to work properly is called its voltage.
How Do We Make a 3 V Battery? 🔋
For example, if you put a 3 V buzzer into a circuit, you need a 3 V battery to make it work. You can create a 3 V battery by joining two 1.5 V cells together.
Think Like a Scientist 1
Question: How can we build and test circuits with different components?
You will need: One 1.5 V cell, a 3 V battery, a switch, a lamp, a buzzer, and connecting wires.
You are going to make:
- A circuit with a cell, a lamp, and a switch.
- A circuit with a 3 V battery, a switch, and a buzzer.
Method:
- In your group, discuss how you will make these circuits. Choose which components you need.
- Identify any risks when making circuits. How will you minimise them?
- Predict what will happen before you make each circuit. Then build your circuits and check if the evidence supports your predictions.
- Test whether adding another cell makes the buzzer sound louder.
- Repeat any observations you are unsure of to make your results more reliable.
Follow-up Questions:
b) Explain why the other two circuits will not work.
Tap to See Answers
- 1: Each circuit should show correct connections between battery, switch, and component.
- 2: Adding another cell made the buzzer louder because the voltage increased.
- 3: Add another cell to increase the brightness of the lamp.
- 4a: Circuit B works because it has a complete path and closed switch.
- 4b: Circuits A and C don’t work because one has a gap (open switch) and the other has a break in connection.
Excellent investigation! You tested your ideas scientifically and explained your results clearly.
Series Circuits 💡
So far, you have made circuits where the electric current has only one path to follow. A circuit like this is called a series circuit.
People often use strings of coloured lamps connected in series to decorate trees, buildings, or rooms for festivals and parties. If one lamp stops working, none of the others will light up, so you have to check each lamp to find the faulty one.
Parallel Circuits 🔋
Is it possible to keep some lamps lit even if one burns out? Yes — you can do this by connecting the lamps so each one has its own separate pathway to the battery. This is called a parallel circuit.
Each pathway in a parallel circuit receives the full circuit voltage. That’s why if one lamp stops working, the others can still shine. You will explore parallel circuits more in your next investigation.
Think Like a Scientist 5.4.2
Question: How do series and parallel circuits compare in brightness and behavior when lamps are added or removed?
You will need: Plastic coated wire, 4 lamps in lamp holders, and two 3 V batteries.
Method:
- Connect the components as shown above in the drawings for both the series and parallel circuits.
- Predict whether both lamps will shine. Decide if one lamp will shine more brightly or if they will both shine the same amount.
- Test your prediction.
- Unscrew one of the lamps and predict what will happen to the remaining lamp. Will it shine more brightly, the same amount, or less brightly?
- Test your prediction again.
- Record your results in a table like this:
| Circuit type | Brightness of lamps (* or ** or ***) |
Does the remaining lamp shine when one is removed? | Does the remaining lamp have same brightness as before? |
|---|---|---|---|
| Series circuit | |||
| Parallel circuit |
Safety: Do not unscrew a lamp immediately after it has been on—it may be hot and could burn your fingers.
Follow-up Questions:
In a series circuit with two lamps and one battery, the lamps will burn _______ brightly than in a parallel circuit with two lamps and one battery.
In a series circuit there is only _______ path for the electric current. If one lamp is removed, the other lamp will _______ light up because the circuit is _______.
In a parallel circuit, each lamp has its own _______. If one lamp is removed, the other lamp will remain lit with the _______ brightness as before.
Extension:
Look at circuits A and B:
a) Identify which circuit is the series circuit and which is the parallel circuit.
b) In which circuit will the lamps shine more brightly? Explain your answer.
Tap to See Answers
- 1: Lamps in the parallel circuit shine more brightly because each receives the full voltage.
- 2: In the series circuit, removing one lamp breaks the circuit, so the other lamp goes out.
- 3: In the parallel circuit, the other lamp remains lit because it still has its own path to the battery.
- 4: Circuit A is series; Circuit B is parallel.
Great work comparing series and parallel circuits! You’ve learned how brightness changes depending on circuit design.