An electric iron has a rating of $750\, W; 200\, V$. Calculate:
$(i)$ The current required.
$(ii)$ The resistance of its heating element.
$(iii)$ Energy consumed by the iron in $2$ hours.

Out of the two,a toaster of $1\, kW$ and an electric heater of $2\, kW$,which has a greater resistance?

There are two electric bulbs,$(i)$ marked $60\, W, 220\, V$ and $(ii)$ marked $100\, W, 220\, V$. Which one of them has higher resistance?

What is the power of a bulb rated at $2.5 \, V$ and $500 \, mA$ (in $, W$)?

$(a)$ Name an instrument that measures potential difference between two points in a circuit. Define the unit of potential difference in terms of $SI$ unit of charge and work. Draw the circuit symbols for $(i)$ variable resistor,$(ii)$ a plug key which is closed.
$(b)$ Two electric circuits $(I)$ and $(II)$ are shown below.
$(i)$ Which of the two circuits has more resistance?
$(ii)$ Through which circuit does more current pass?
$(iii)$ In which circuit is the potential difference across each resistor equal?
$(iv)$ If $R_{1} > R_{2} > R_{3}$,in which circuit will more heat be produced in $R_{1}$ as compared to the other two resistors?

State $Ohm's$ law. Calculate the resistance of a conductor,if the current flowing through it is $0.2 \, A$ when the applied potential difference is $0.8 \, V$.