- Light can cause a change in conductivity of some semi-conductors
- When light is absorbed by the material it causes more electrons to be available for conduction
- An increase in the number of conduction electrons reduces the resistance
Resistance of an LDR depends on the light intensity falling on it
Graph of light intensity and resistance for an LDR
LDRs are used for automatic street lights
The graphs show various possible relationships between current and voltage through a component.
Which graph best represents the relationship between the current and voltage of an LDR?
Step 1: Consider the relationship between light intensity and resistance
Step 2: Consider a relevant equation
Step 3: State the conclusion
to absolutely everything:
the (exam) results speak for themselves:
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Joanna obtained her undergraduate degree in Natural Sciences from Cambridge University and completed her MSc in Education at Loughborough University. After a decade of teaching and leading the physics department in a high-performing academic school, Joanna now mentors new teachers and is currently studying part-time for her PhD at Leicester University. Her passions are helping students and learning about cool physics, so creating brilliant resources to help with exam preparation is her dream job!