IB Physics SL B.5.4 Ohmic Behaviour

Practise stating Ohm's law with its constant-temperature condition and deciding from current-voltage data whether resistance stays constant or changes with operating point.

Syllabus
First assessment 2025
Objective
—
Level
SL

Exam points

  • state that V is proportional to I only when temperature and other physical conditions remain constant
  • identify an ohmic component from a straight V-I graph through the origin and constant gradient
  • explain non-ohmic behaviour through changing resistance, such as heating of a filament

B.5.4—Ohmic behaviour question 1

[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.5.4—Ohmic behaviour question 1 — IB Physics SL

Explain whether or not the filament obeys Ohm's law.

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