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 $0.8 \, V$.

Two wires $A$ and $B$ are of the same metal,have the same area of cross-section,and have their lengths in the ratio $2:1$. What will be the ratio of currents flowing through them respectively,when the same potential difference is applied across each of them?

When a high resistance voltmeter is connected directly across an electric bulb,its reading is $2 \ V$. An electric cell is sending a current of $0.4 \ A$ (measured by an ammeter) in the electric circuit.
$(a)$ Draw the circuit.
$(b)$ Find the resistance of the electric bulb.
$(c)$ State the law that is applied for making these calculations. If a graph is plotted between $V$ and $I$,show the nature of the graph obtained.

What will happen to the resistance of the circuit,if the current through it is doubled?

What are the factors on which the resistivity of a material depends?

An electric heater draws a current of $2\;A$ when connected to a voltage source of $120\;V$. What is the resistance of the heater coil?