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# Potential Dividers question watch

1. A light dependent resistor and a fixed resistor of resistance 10 000 ohms are connected in series with a power supply of 5.0V. The negative terminal is earthed i.e. it may be taken as 0V. In the dark, the potential of point X (between the resistor and LDR) is 0.21V; when more light falls on the LDR the potential of X rises to 4.2V. Calculate the resistance of the LDR in both the situations.
2. What voltage is across the fixed resistor in both cases?
How much current flows?
Given that you know the voltage across and current through the LDR, you can calculate its resistance.

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Updated: February 4, 2018
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