Here are the solutions for questions A16 and A17: A16 Which fuse is most suitable for use in a 2000W electric heater connected to a 240V supply? Step 1: Calculate the operating current ($I$) of the electric heater using the formula $P = VI$, where $P$ is power and $V$ is voltage. $$I = \frac{P}{V}$$ $$I = \frac{2000 \text{ W}}{240 \text{ V}}$$ $$I = \frac{200}{24} \text{ A}$$ $$I = \frac{25}{3} \text{ A}$$ $$I \approx 8.33 \text{ A}$$ Step 2: Choose a fuse rating that is slightly higher than the operating current to allow for normal operation but will blow if there is an overload. Comparing $8.33 \text{ A}$ with the given options: A: 3 A (too low) B: 5 A (too low) C: 10 A (suitable, as it's the next standard rating above 8.33 A) D: 13 A (also above, but 10 A provides closer protection) The most suitable fuse is 10 A. The correct option is C. --- A17 What is the operating resistance of an electric lamp rated 60W, 240V? Step 1: Use the formula relating power ($P$), voltage ($V$), and resistance ($R$): $P = \frac{V^2}{R}$. Rearrange the formula to solve for resistance: $$R = \frac{V^2}{P}$$ Step 2: Substitute the given values into the formula. $$R = \frac{(240 \text{ V})^2}{60 \text{ W}}$$ $$R = \frac{240 \times 240}{60} \Omega$$ $$R = \frac{57600}{60} \Omega$$ $$R = 960 \Omega$$ Step 3: Compare the calculated resistance with the given options. A: 4 $\Omega$ B: 300 $\Omega$ C: 960 $\Omega$ D: 14 400 $\Omega$ The calculated resistance is $960 \Omega$. The correct option is C.