Figure 11 shows how the National Grid connects a power station to consumers - AQA - GCSE Physics - Question 8 - 2023 - Paper 1

The correct equation is:

$P = I R$

Using the power loss formula, we have:

$1.60 \times 10^9 = 2000^2 \times R$

Rearranging gives:

$R = \frac{1.60 \times 10^9}{2000^2}$

Calculating this results in:

$R = 400 \; (\Omega)$

The equation is:

$\text{Efficiency} = \frac{\text{Useful Energy Output}}{\text{Total Energy Input}}$

Using the efficiency equation:

$\text{Useful Energy Output} = \text{Efficiency} \times \text{Total Energy Input}$

Substituting in the values gives:

$\text{Useful Energy Output} = 0.992 \times 34.2 \; \text{GJ} = 33.9 \; \text{GJ}$