A 100 W heater is connected to a 240 V supply. Calculate: (a) the current drawn by the heater. (b) the resistance of the heater.

The power ($P$), voltage ($V$), and current ($I$) are related by the formula $P = V \times I$.
Given $P = 100\, \text{W}$ and $V = 240\, \text{V}$.

$$I = \frac{P}{V} = \frac{100\, \text{W}}{240\, \text{V}}$$ $$I = 0.4166...\, \text{A}$$ $$I \approx 0.417\, \text{A}$$

The current drawn is $\boxed{\text{0.417 A}}$.

The power ($P$), voltage ($V$), and resistance ($R$) are related by the formula $P = \frac{V^2}{R}$.
Given $P = 100\, \text{W}$ and $V = 240\, \text{V}$.

$$R = \frac{V^2}{P} = \frac{(240\, \text{V})^2}{100\, \text{W}}$$ $$R = \frac{57600\, \text{V}^2}{100\, \text{W}}$$ $$R = 576\, \Omega$$

The resistance of the heater is $\boxed{\text{576 } \Omega}$.