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Lesson: Chapter 19 — Current Electricity

19.6. Resistors 7 of 7

Question 7

What happens to a light dependent resistor in the dark?

The right answer is the one marked above.

Its resistance is high. When there is little light the resistance of an LDR is high; when light is present it is low.

This is what makes an LDR a sensor. It turns "how bright is it?" into "how much current flows?", which is why street lamps use them to switch on at dusk.

Answer the question to continue.