IB Physics SL B.5.5 Electrical power Question Bank
Practise IB Physics SL B.5.5 by applying P=IV, I²R and V²/R to circuits, motors, lamps and cable losses.
- Syllabus
- First assessment 2025
- Course
- Physics SL
- Level
- SL
Practise IB Physics SL B.5.5 by applying P=IV, I²R and V²/R to circuits, motors, lamps and cable losses.
Part 2 Electric current and resistance
The graph below shows how the current I in a tungsten filament lamp varies with potential difference V across the lamp.

Two identical filament lamps are connected in series with a cell of emf 6.0 V and negligible internal resistance. Using the graph on page 26, calculate the total power dissipated in the circuit.
each lamp has a potential difference of 3.0 V so current equals 0.35 A; (accept answers in range 0.34 to 0.35 A)
2.1 W; (accept answers in range 2.0 to 2.1 W)
Award [1] for answers that use voltage 6.0 V with current 0.52 A to get P = 3.1 W.