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:

$P = I^2 R$

Using the power loss formula:

$P = I^2 R$

Substituting the values:

$1.60 imes 10^9 = 2000^2 imes R$

Solving for R:

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

Calculating:

$R = 400 \, \Omega$

The equation is:

$\text{efficiency} = \frac{\text{useful energy output}}{\text{total energy input}}$

Using the efficiency equation:

$0.992 = \frac{\text{useful energy output}}{34.2}$

Rearranging to find useful energy output:

$\text{useful energy output} = 0.992 \times 34.2$

Calculating:

$\text{useful energy output} = 33.9 \text{ GJ}$