6. (a) A technician investigates a light-dependent resistor (LDR) connected in series with a 120 Ω resistor and a voltage source - Edexcel - GCSE Physics - Question 6 - 2015 - Paper 1

To find the current in the LDR, we apply Ohm's law, which is given by the formula:

$I = \frac{V}{R}$

Substituting the values we have:

$I = \frac{7.2 \text{ V}}{185 \Omega}$

Calculating this gives:

$I \approx 0.03892 \text{ A}$

This rounds to approximately 0.039 A.

The resistance of the LDR varies based on light exposure. In bright sunlight, its resistance decreases, allowing more current to flow through the circuit. Conversely, in the dark, the resistance increases, resulting in less current flow.