IB Physics SL B.5.5 Electrical Power

Practise selecting P = IV, I²R or V²/R according to shared current or voltage, using graph operating points and applying power reasoning to transmission and alternating signals.

Exam points

calculate P = IV from the current and potential difference at the same component operating point
use I²R for series comparisons or V²/R for parallel comparisons based on the shared quantity
explain high-voltage transmission through lower current and reduced I²R power loss

[Maximum number: 2]

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.

Figure for Question B.5.5—Electrical power question 1 — IB Physics SL

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.

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B.5.5—Electrical power question 1