If $2 \times 10^{-3} \text{ J}$ of work is done in moving a particle carrying a charge of $10 \times 10^{-6} \text{ C}$ from infinity to a point $P$, what will be the potential at the point $P$ (in $\text{ V}$)?

$A$ conducting wire offers resistance to the flow of electrons because electrons repel each other in the wire.

Which instrument is used to measure electric current?

How is an ammeter connected in a circuit?

$(a)$ Resistivity of iron is $10 \times 10^{-8} \; \Omega m$ and of mercury is $94 \times 10^{-8} \; \Omega m$. Which among iron and mercury is a better conductor? Give reason.
$(b)$ Resistivity of a material $A$ is in the range of $10^{10}-10^{14} \; \Omega m$ while that of $B$ is in the range of $10^{-6}-10^{-8} \; \Omega m$. Which of the two will behave as an insulator and why?

$(a)$ 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.