Changing the number of components in a circuit
This Topic is About...
- I will investigate how changing the number or type of components in a circuit makes a lamp shine more brightly or less brightly.
- I will identify risks and carry out practical work safely.
- I will make predictions and check if results support or do not support my predictions.
- I will describe simple patterns in results and make conclusions from the results.
You’re going to be a science explorer!
Key Words
- battery
- brightness
- brightly
- dimly
Tap to Learn the Meanings!
- battery: A device that stores and provides electrical energy.
- brightness: How much light something gives off or how well it shines.
- brightly: Giving out a strong, clear light.
- dimly: Giving out only a small or weak amount of light.
Great work! You’re learning new words about light and electricity.
Cells and batteries
So far you have mostly made circuits with one cell. Each cell stores 1.5 V of electricity. When we have two or more of these cells connected together we call it a battery. The car battery in the picture is 12 V.
Your teacher used two cells in the experiment looking at whether water conducted electricity. When the cell or battery is part of a circuit, the stored energy pushes electricity around the circuit. In the next activity you need to use a 3 V battery.
Let’s Investigate!
Question: What happens when we change the number of components in a circuit?
Equipment: Three 1.5 V cells in cell holders, three lamps in lamp holders, a switch, wire, a sharp knife or wire trimming tools, scissors, a stick
Prepare your table of results:
| Circuit | Brightness of lamps |
|---|---|
| 1. 3V battery, three lamps | |
| 2. 3V battery, two lamps | |
| 3. 3V battery, one lamp | |
| 4. 4.5V battery, three lamps | |
| 5. 3V battery, three lamps (changed setup) |
Method:
- Make a 3V battery by joining two cells together, ensuring the positive and negative terminals are aligned correctly.
- Use scissors to cut the wire into short lengths. Build circuit 1 using three lamps in lamp holders and a switch.
- Be careful! If using a knife to strip wire plastic, wait for your teacher’s help or use wire trimming tools.
- Predict what will happen when you close the switch. Then close the switch and observe the lamps.
- Open the switch and predict what will happen next. Observe again.
- Make circuit 2 by removing one lamp and holder (two lamps left). Predict and test again.
- Now make circuit 3 by leaving just one lamp in the circuit. Observe and record.
- Next, create circuit 4 by using three cells (4.5V) and three lamps. Predict and observe brightness.
- Finally, make circuit 5 by removing one cell from circuit 4 (back to 3V). Compare brightness and record your results.
Questions:
- Identify two risks when doing this investigation.
- Explain how to stay safe and avoid these risks.
- Did the lamps shine more brightly or dimly when you removed one lamp? Why?
- What happened when you used one lamp and three cells? Why?
- Did the lamps shine more brightly or dimly when you removed one cell? Why?
- Identify a pattern: The lamps shine less/more brightly when you add more lamps. The lamps shine less/more brightly when you add more cells.
- Complete the conclusion: Changing the number of ________ or ________ in a circuit can make a lamp ________ or ________.
- Which type of scientific enquiry did you use in this investigation?
How am I doing?
- How well did your partner do in the investigation?
- Was your partner confident in connecting the components of the circuit?
- How well did they add or remove components and reconnect the circuit?
- Did they need some help or manage it on their own?
- How well did your partner record their results?
Tap to See Answers
- 1: Risks include electric shock from exposed wires or burns from overheated bulbs.
- 2: Stay safe by keeping wires insulated and switching off the circuit before adjusting it.
- 3: Lamps shone more brightly when one lamp was removed because more current flowed through the remaining lamps.
- 4: With one lamp and three cells, the lamp was very bright because more voltage increased the current.
- 5: Lamps shone more dimly when one cell was removed because there was less energy supplied.
- 6: Pattern: The lamps shine less brightly when more lamps are added; they shine more brightly when more cells are added.
- 7: Changing the number of cells or lamps in a circuit can make a lamp brighter or dimmer.
- 8: This was a fair test using observations and pattern seeking to draw conclusions.
Brilliant work! You’ve investigated how voltage and components affect the brightness of lamps in a circuit.
