In a boiler, energy is transferred to water at a rate of 40kW - Edexcel - A-Level Physics - Question 6 - 2023 - Paper 1

To calculate the efficiency of the boiler, we use the formula:

ext{Efficiency} = rac{ ext{Useful Output Energy}}{ ext{Total Input Energy}}

In this case, the Useful Output Energy is 40 kW (energy transferred to water) and the Total Input Energy is the sum of the Useful Output Energy and Power Loss:

$ext{Total Input Energy} = 40 ext{ kW} + 4 ext{ kW} = 44 ext{ kW}$

Now substituting the values into the efficiency formula:

ext{Efficiency} = rac{40 ext{ kW}}{44 ext{ kW}} = 0.9090...

Rounding this value gives us approximately 0.91. Therefore, the efficiency of the boiler is about 0.91.