The unit of electric power may also be expressed as:

Define resistance of a conductor. State the factors on which resistance of a conductor depends. Name the device which is often used to change the resistance without changing the voltage source in an electric circuit.
Calculate the resistance of $50 \, m$ length of wire of cross-sectional area $0.01 \, mm^2$ and of resistivity $5 \times 10^{-8} \, \Omega \, m$.

If a $12 \ V$ battery is connected to the arrangement of resistances given below,calculate
$(i)$ the total effective resistance of the arrangement and
$(ii)$ the total current flowing in the circuit.

An electric heater consumes $1.1 \,kW$ power when $220 \,V$ voltage is applied to it. How much current will be flowing through it (in $,A$)?

Why is heat produced when a current is passed through a conductor?

Two students perform experiments on series and parallel combinations of two given resistors $R_{1}$ and $R_{2}$ and plot the following $V-I$ and $I-V$ graphs. Which of the graphs is (are) correctly labelled in terms of the words 'series' and 'parallel'? Justify your answer.