Thursday, 7 May 2015

LDR response to variations in light intensity

Equipment

LDR
Ammeter
Voltmeter
6V power supply
Connecting leads
Desk lamp
Ruler

Method.

Connect the LDR and ammeter in series with the power supply. Connect the voltmeter in parallel to the LDR.
Set the LDR up so it is 10cm from the bulb.
Switch on the lamp and record the ammeter and voltmeter readings. Switch off the lamp, then back on and repeat the readings. Repeat once more.
Move the LDR 5cm further from the bulb and take another 3 sets of readings.
Continue until you reach 40cm from the bulb.

Take the voltage reading and divide by the current to find the resistance of the LDR in each case.

Safety

The bulb being used may get hot. Care should be taken to let it cool before packing away.