Interpreting I–V graphs
I can take readings from I–V graphs and use these to describe the changing resistance of a component.
- Year 10
- AQA
Interpreting I–V graphs
I can take readings from I–V graphs and use these to describe the changing resistance of a component.
Lesson details
Key learning points
- In forward–bias, a diode has a very small resistance when the p.d. is larger than the threshold voltage.
- In reverse–bias, a diode has a very large resistance and very little current can flow.
- The greater the p.d. across a component, the larger the push on electric charges in the component.
- The resistance of a component is calculated from an I–V graph using pairs of readings and the equation R = V ÷ I.
- The greater the current through a component, the larger the heating effect on it.
Keywords
Reverse–bias - When a diode is reverse–biased, it prevents current from flowing.
Forward–bias - When a diode is forward–biased, it allows current to flow.
Threshold p.d. - The threshold p.d. is the potential difference at which a diode allows current to flow.
Fuse - A fuse is a component that has a wire that melts if the current is too high.
Ion lattice - In a solid metal, the regular and repeating pattern that metal ions are arranged in is known as an ion lattice.
Common misconception
Pupils often cannot apply the main I–V graphs to similar components.
Describe how the p.d. and current in components behaves to draw out similarities that can be used to describe unfamiliar components.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is the function of a diode?
Q2.What does it mean when a diode is in reverse bias?
Q3.Which of these has a symmetrical I-V graph for both positive and negative p.d.?
Q4.Which of the following correctly describes how a fuse wire works?
Q5.What is the resistance of a diode if it allows 0.16 A to flow when the p.d. across it is 0.8 V?
Q6.How does this component work?
Assessment exit quiz
6 Questions
Q1.The characteristics of which component are shown by this I-V graph?
Q2.The characteristics of a diode are shown by this I-V graph. What is its threshold voltage?
