What equation links current (I), potential difference (V) and power (P)? Tick (✓) one box - AQA - GCSE Physics - Question 11 - 2022 - Paper 1

To calculate the current (I) in the tile, we use the formula:

$P = V \times I$

Given:

• Power output, $P = 4.4 \text{ W}$
• Potential difference, $V = 40 \text{ V}$

Substituting the known values:

$4.4 = 40 \times I$

Now, solve for I:

$I = \frac{4.4}{40} = 0.11 \text{ A}$

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

$\text{Efficiency} = \frac{\text{Useful power output}}{\text{Total power input}}$

To find the useful power output of the LED light, we use the efficiency formula:

$\text{Efficiency} = \frac{\text{Useful power output}}{\text{Total power input}}$

Given:

• Efficiency = 0.85
• Total power input = 4.0 W

We rearrange the formula to find the useful power output:

$\text{Useful power output} = \text{Efficiency} \times \text{Total power input}$

Substituting the known values:

$\text{Useful power output} = 0.85 \times 4.0 = 3.4 \text{ W}$