How It Works: Why Resistance Increases with Temperature (Metals)
Part of Resistance & Ohm's Law — GCSE Physics
This how it works covers How It Works: Why Resistance Increases with Temperature (Metals) within Resistance & Ohm's Law for GCSE Physics. Revise Resistance & Ohm's Law in Electricity for GCSE Physics with 14 exam-style questions and 30 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 6 of 16 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 6 of 16
Practice
14 questions
Recall
30 flashcards
⚙️ How It Works: Why Resistance Increases with Temperature (Metals)
At higher temperatures, the metal ions in the wire vibrate more vigorously. This increases the chance that a free electron will collide with an ion as it moves through the wire.
Each collision slows the electron down, transferring some of its kinetic energy to the ion as thermal energy (heat). More collisions = more opposition to flow = higher resistance.
This is why a filament lamp has a non-linear V-I graph: as more current flows, the filament heats up, its resistance increases, which limits further current increases. The graph curves upward (V increases faster than I).
For a thermistor, the opposite happens: it's made of semiconductor material where higher temperature frees more charge carriers, so resistance decreases as temperature rises. This makes thermistors useful as temperature sensors in thermostats and fire alarms.