(a)

State Ohm's Law.

(b)

Name and define the physical quantity determined by the slope of V - I curve given in the diagram. Use this graph to find the value of this physical quantity in SI units.

(b)

(c)

Establish the relationship between $\displaystyle 1$ kWh and $\displaystyle 1$ joule.

(a) The potential difference V across the ends of a given metallic wire in an electric circuit is directly proportional to the current flowing through it provided its temperature remains the same. / \(\displaystyle \mathrm{V} \alpha \mathrm{I}\) or \(\displaystyle \mathrm{V}=\mathrm{IR}\) (temperature remaining constant)

(b) Resistance Resistance is the property of a conductor to resist the flow of charges. \[\begin{aligned} \mathrm{R}= & \text { slope }=\frac{y_{2}-y_{1}}{x_{2}-x_{1}} / \frac{\mathrm{V}}{\mathrm{I}}=\frac{6-0}{0.8-0} \\ & =\frac{60}{8}=7.5 \Omega \end{aligned} \]

(c) \(\displaystyle 1 \mathrm{kWh}=1000 \frac{J}{\sec } \times 3600 \mathrm{sec}\) \(\displaystyle 1 \mathrm{kWh}=3.6 \times 10^{6} \mathrm{~J}\)