Lighting a home
Home lights use parallel branches, so one switched-off bulb does not turn every other light off.
Key idea: parallel branches work independentlyCircuits
Find out what makes electric current flow and why the way we connect components matters.
Why it matters
Where do we use this?
Electric circuits carry energy through almost every device we use. Understanding a simple loop helps us use electricity safely and design systems that keep working.
Protecting devices
Fuses and circuit breakers open a circuit when too much current could heat wires dangerously.
Key idea: current must be controlledPortable electronics
Phones and laptops manage battery voltage and component resistance to deliver the current each part needs.
Key idea: voltage pushes currentFinding faults
Technicians follow the loop and measure voltage or current to locate a broken connection.
Key idea: a break stops the loopOur driving questionWhat controls how much current flows through a circuit?
Explore
Try it first
Close the switch, change the voltage and resistance, then compare Series and Parallel.
V 6.0 VI total 0.75 Aper bulb 0.75 AQ 0.00 C
Notice: current flows only when the switch makes a complete path.
Investigate
Three guided experiments
Make a prediction before touching the controls. Then test it and explain the evidence in your own words.
Procedure
- Choose Series and close the switch.
- Watch the moving charges and bulb brightness.
- Open the switch and compare.
Record
Describe what stops when the path is broken.
Explain
What is happening?
Voltage pushes
Voltage is the energy push that drives charges around a complete circuit.
Resistance slows
Resistance makes it harder for current to flow. More resistance means less current.
Connections matter
Series components share one path. Parallel components sit on separate branches.
Ohm's law
I = V / R- I
- current in amperes
- V
- voltage in volts
- R
- resistance in ohms
Worked example
A 6 V battery across 4 Ω gives I = 6 ÷ 4 = 1.5 A.
Check your model
Can you predict the pendulum?
Extend
Take it further
Try to make the same total current with two different voltage and resistance settings. What ratio stays the same?