This deep dive covers What Affects the Resistance of a Wire? within Resistance & Ohm's Law for GCSE Physics. Revise Resistance & Ohm's Law in Electricity for GCSE Physics with 16 exam-style questions and 30 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 4 of 16 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
🔧 What Affects the Resistance of a Wire?
Four factors:
- Length — longer wire = more resistance (R ∝ L)
- Cross-sectional area — thicker wire = less resistance (R ∝ 1/A)
- Material — different materials have different resistivities
- Temperature — for metals, hotter = more resistance
Why length increases resistance:
- Electrons must travel further through the material
- More collisions with metal ions along the way
- More opposition to flow overall
Why thickness decreases resistance:
- More pathways for electrons to flow side-by-side
- Like a wider road with more lanes — less congestion
- Less crowded = easier flow
Practice questions for Resistance & Ohm's Law
Which of the following best describes electrical resistance?
Explain what is meant by an ohmic conductor.
Quick recall flashcards
Unit of resistance?
Ohm (Ω)
Ohm's Law equation?
V = IR where V = voltage (V), I = current (A), R = resistance (Ω)