LDR demonstration
Equipment:
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Power supply (up to 15V)
Light bulb
LDR
100 Ohm resistor
Connecting leads
Set up the circuit as below:
Turn the lights off in the classroom. Get the room as dark as possible.
Turn the power on. Set the power supply to at least 13 V. The bulb should be
lit.
Using a bright light source (torch on mobile phone or similar), shine the light
directly onto the LDR. There should be a noticeable change in the brightness
of the bulb. Explain that this is similar to the light sensor in their phones,
laptops and tablets which change brightness depending on the
environment.