CAIE IGCSE Physics Resistor Lamp and Diode I–V Graphs
Practise sketching and identifying I–V graphs for an ohmic resistor, filament lamp and diode, then explain each shape through resistance or conduction.
- Syllabus
- 2026–2028
- Course
- Physics 0625
Exam points
- identify a constant-resistance conductor from a straight I–V line through the origin
- explain a filament lamp's flattening I–V curve as heating that increases its resistance
- identify a diode from negligible reverse current and conduction after its forward threshold
4.2.4.4—And explain the current–voltage graphs question 1
Fig. 6.2 shows two light-emitting diodes (LEDs) connected in parallel in a circuit. R is a red LED and G is a green LED.
The voltmeter across the LEDs shows a potential difference (p.d.) of 2.0 V.
Fig. 6.2
Fig. 6.3 shows a current-p.d. graph for the LEDs.
Fig. 6.3
Use Fig. 6.3 to determine the current in the ammeter.
current =
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