Using heating effect as the reference, explain what is meant by the root-mean-square (r.m.s.) value of an alternating current.
Fig. 10.1 and Fig. 10.2 show how the two currents $I_1$ and $I_2$ vary with time $t$.
From Fig. 10.1, find the peak value and the r.m.s. value of current $I_1$.
From Fig. 10.2, determine the peak value and the r.m.s. value of current $I_2$.
The dependence of the house supply voltage $V$ on time $t$ is described by $V = 240\sin kt$, where $V$ is measured in volts, $t$ is measured in seconds and $k$ is a constant with unit $\text{rad s}^{-1}$.
The supply voltage has frequency $50\,\text{Hz}$. Determine $k$ to two significant figures.
The supply voltage is connected to a heater. The heater has mean power $3.2\,\text{kW}$. Calculate the resistance of the heater.