Quick answer: Ohm's law says that the current through an ohmic conductor is proportional to the potential difference across it, so V = I × R. This grade 8 science test on ohm's law has 8 questions worth 20 marks, to do in 45 minutes: meters, find the current and unit conversion. The mark scheme is on a separate page; free printable PDF.
This grade 8 science test on ohm’s law test works like a real class test. The mark scheme is on a separate page, so revise with the lesson first.
This test lasts 45 minutes and is worth 20 marks. Show the formula, the substitution and the answer with a unit in every calculation. Convert mA and kΩ before you calculate.
Level: Grade 8 science (Year 9 · Class 8) · Curriculum: MS-PS2-3
Ohm’s law test: the test questions
Question 1 Meters (2 marks)
- State how an ammeter is connected to a component. (1 mark)
- State how a voltmeter is connected. (1 mark)
Question 2 Find the current (3 marks)
A 45 Ω resistor is connected to a 9.0 V battery.
- Calculate the current. (2 marks)
- The resistance is doubled with the same battery. Calculate the new current. (1 mark)
Question 3 Unit conversion (2 marks)
- Convert 330 mA to A. (1 mark)
- Convert 2.2 kΩ to Ω. (1 mark)
Question 4 Reading a graph (3 marks)
The graph shows readings for a resistor.
- Calculate the resistance. (2 marks)
- Use the graph to find the current at 6.0 V. (1 mark)
Question 5 Filament lamp (3 marks)
- Explain why the I–V graph of a filament lamp is a curve and not a straight line. (3 marks)
Question 6 An LED resistor (3 marks)
An LED needs 2.0 V and passes 0.020 A. It is in series with a resistor on a 6.0 V supply.
- Calculate the potential difference across the resistor. (1 mark)
- Calculate the resistance needed. (2 marks)
Question 7 Wet hands (2 marks)
- Explain why touching a mains wire with wet hands is more dangerous than with dry hands. (2 marks)
Question 8 Wire resistance (2 marks)
- State two ways of lowering the resistance of a metal wire. (2 marks)
