Module 3 · Practice
Practice questions
Three difficulty levels. Have a proper go before checking the answers.
Section A — Easy
Recall and short answers
State the unit of:
Write down the equation linking voltage, current and resistance.
Where in a circuit do you connect:
Name three magnetic materials.
Give two ways to make an electromagnet stronger.
Section B — Medium
Calculation and short application
Calculate the resistance of a heater that draws a current of 4A from a 230V supply.
A 12V battery is connected to a 6Ω bulb. Calculate the current through the bulb.
Three identical bulbs are in series with a 6V battery. State the voltage across each bulb and explain.
Christmas lights wired in series go out completely when one bulb breaks. Explain why.
A balloon rubbed on a jumper picks up small bits of paper. Explain what is happening in terms of electrons and charge.
Why does a scrap-yard crane use an electromagnet rather than a permanent magnet?
Section C — Hard
Extended thinking and tougher calculation
A circuit has two 4Ω resistors in series with a 12V battery.
The same two 4Ω resistors are now in parallel across the 12V battery. State the voltage across each resistor and the current in each branch.
Design an investigation to find out how the number of turns on a coil affects the strength of an electromagnet. State the variables.
Two identical bulbs are connected in series, and another two identical bulbs are connected in parallel — all to identical 6V batteries. Compare the brightness of one bulb in the series circuit with one in the parallel circuit, with reasoning.