$100 \, J$ of heat is produced each second in a $4 \, \Omega$ resistance. Find the potential difference across the resistor. (in $, V$)

Distilled water acts as ........ for electricity.

An electric bulb rated $220 \, V, 60 \, W$ is working at full efficiency. $(i)$ State the resistance of the coil of the bulb. Another identical bulb is connected in series with the first one and the system is connected across the mains as shown below. $(ii)$ State the rate of conversion of energy in each bulb. $(iii)$ Calculate the total power. $(iv)$ What will be the total power if the bulbs are connected in parallel?

Give a single word for $\frac{1 \text{ joule}}{1 \text{ coulomb}}$.

$(a)$ What is an electric circuit?
$(b)$ Calculate the number of electrons that flow per second to constitute a current of one ampere. The charge on an electron is $1.6 \times 10^{-19} \ C$.
$(c)$ Draw an electric circuit for studying Ohm's law. Label the circuit components used to measure electric current and potential difference.

Should the resistance of an ammeter be low or high? Give reason.