Year 10 - Science
Resistance of a hot metal
Circuit components
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit explores current, resistance, and potential difference. It covers circuit design for lamps, diodes, and thermistors, and emphasises planning experiments, data interpretation, and presenting scientific conclusions.
Lesson Summary
You will learn to explain why the resistance of a metal filament changes as the p.d. across it increases.
Key Notes
- As the p.d. across a filament lamp increases, it gets hotter and current through it increases in a non-ohmic way.
- The greater the p.d. across a filament lamp, the greater its resistance.
- A metal is made of a lattice of positively charged ions with negatively charged electrons between.
- As a current flows through metal, electrons moving through the ion lattice cause it to vibrate more vigorously.
- The more vigorously the ions (ion lattice) vibrate, the hotter the metal and the higher its resistance.
Vocabulary To Learn
- filament lamp: a type of lamp that uses a hot wire to emit light
- ohmic conductor: a conductor for which the current is directly proportional to the p.d.
- directly proportional: a relationship between variables in which one is a multiple of the other
- metal ion: a metal atom that has lost one or more outer electrons and has become positively charged
- free electron: an electron from the outer shell of an atom that is free to move from ion to ion through a metal
Common Mistakes To Avoid
- The gradient of an I-V graph is equal to 1/R because I = V ÷ R.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
As the p.d. across a filament lamp increases, it gets hotter and current through it increases in a non-ohmic way. The greater the p.d. across a filament lamp, the greater its resistance.
2. Define this scientific word and use it in context. 'filament lamp'
a type of lamp that uses a hot wire to emit light. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: The gradient of an I-V graph is equal to 1/R because I = V ÷ R. Correction: Explain how the equation for a straight line graph y = mx + c does not apply in this case because the graph is not a straight line.
More Lessons In This Unit
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