PHYISCS alevel ( can anyone please solve this one )

A light sensor consists of a 5.0V cell, an LDR and a 5.0k Ohm resistor in series with each other. A voltmeter is connected in parallel with the resistor. When the LDR is in darkness, the voltmeter reads 2.2V.

a) Calculate the pd across the LDR (= 5.0 - 2.2 = 2.8v)
b) Calculate the resistance of the LDR when the voltmeter reads 2.2V
c) Describe how the voltmeter reading would change if the LDR were exposed to daylight with no adjustment made to the variable resistor.

Reply 1

Joinedup

Have you done potential divider circuits (sometimes called voltage divider)?

Making a light detector with a LDR and a resistor in series is a classic application of potential divider theory.