An engineering company has invented pavement tiles that generate electricity as people walk on them - AQA - GCSE Physics - Question 11 - 2022 - Paper 1

We can calculate the current using the formula for power:

$P = V imes I$

Substituting the given values:

$4.4 = 40 imes I$

Rearranging gives:

$I = \frac{4.4}{40}$

Calculating this provides:

$I = 0.11 ext{ A}$

The equation that links efficiency with total power input and useful power output is:

$\text{Efficiency} = \frac{\text{useful power output}}{\text{total power input}}$

To find the useful power output, we can use the efficiency formula:

$\text{Efficiency} = \frac{\text{useful power output}}{\text{total power input}}$

Substituting the known values:

$0.85 = \frac{P}{4.0}$

Rearranging gives:

$P = 0.85 \times 4.0$

Calculating this yields:

$P = 3.4 ext{ W}$