6 (a) The diagram shows a circuit with two resistors, R and S - Edexcel - GCSE Physics - Question 6 - 2018 - Paper 1

To find the potential difference across resistor R, we can use Ohm's Law, which states:

$V = I imes R$

Where:

• $V$ is the potential difference (voltage) across the resistor,
• $I$ is the current flowing through the resistor,
• $R$ is the resistance of the resistor.

Given that the current through R is 0.40 A and its resistance is 15 Ω, we can calculate:

$V = 0.40 ext{ A} imes 15 ext{ Ω} = 6 ext{ V}$

Thus, the potential difference across R is 6.0 V.