An electric bulb of resistance $480 \Omega$ is connected to a $220 \text{ V}$ main. Find the amount of electrical energy consumed in $10 \text{ seconds}$. (in $J$)

What is the electrical resistivity of a material? What is its $SI$ unit? Describe an experiment to study the factors on which the resistance of a conducting wire depends.

What is the device (meter) used to measure electric potential difference called?

$(a)$ State the commercial unit of electric energy and find its relation with its $SI$ unit.
$(b)$ The current through a resistor is made three times its initial value. Calculate how it will affect the heat produced in the resistor.
$(c)$ Find the increase in the amount of heat generated in a conductor if another conductor of double resistance is connected in the circuit,keeping all other factors unchanged.

The $I-V$ graphs of two resistors,and their series combination,are shown below. Which one of these graphs represents the series combination of the other two? Give reasons for your answer.

$V-I$ graphs for two wires $A$ and $B$ are shown in the figure. If both the wires are made of the same material and are of equal thickness,which of the two is of more length? Give justification for your answer.