A 12 V battery is connected to a 30 Ω resistor. (a) Calculate the current. (b) Calculate the power dissipated. (3 marks)
Hint: (a) Rearrange V=IR to I=V/R. (b) P = IV (use your calculated current and given voltage).
+30 XP
1 markFilament lamp characteristicAQA 8463 style
Why does the resistance of a filament lamp increase as the voltage across it increases?
A The filament gets shorter as it heats up
B Higher voltage causes the filament to melt partially
C Higher current heats the tungsten filament — higher temperature increases resistance
D Resistance is directly proportional to voltage for all components
3 marksRequired practicalAQA 8463 P2 style
Describe how to carry out an experiment to determine the I-V characteristic of a resistor. Include the circuit setup and the measurements taken. (4 marks)
Hint: Circuit: series with ammeter, parallel voltmeter. Method: vary voltage, record V and I pairs. Plot I vs V.
+30 XP
1 markLDR applicationAQA 8463 style
An LDR is used in a circuit to control a streetlight. As it gets dark, the LDR resistance:
A Decreases, causing the voltage across it to fall, turning the light off
B Increases, causing the voltage across it to rise, which can trigger the light to switch on
C Stays constant, regardless of light level
D Decreases, triggering the lamp off
3 marksCharge flow — time in minutesAQA 8463 style ⚡ Unit conversion trap
A battery supplies a current of 130,000 A. Calculate the charge flow from the battery in 5 minutes. Give your answer in coulombs. (3 marks)
Trap: Time is given in MINUTES. Convert to seconds first: 5 minutes = 5 × 60 = 300 seconds. Then Q = I × t. Unit is coulombs (C), not watts or joules.