(A) State two applications of Joule's heating in domestic electric circuit. (B) (a) Establish the relationship between the commercial unit of…

\[\begin{aligned} & =3.6 \times 10^{6} \text { watt second } \\ & =3.6 \times 10^{6} \text { Joule }(\mathrm{J}) \end{aligned} \]

\[\begin{aligned} & \frac{1}{\mathrm{R}_{\mathrm{p}}}=\frac{1}{\mathrm{R}_{1}}+\frac{1}{\mathrm{R}_{2}}+\frac{1}{\mathrm{R}_{3}} \\ & \frac{1}{\mathrm{R}_{\mathrm{p}}}=\frac{1}{2 \Omega}+\frac{1}{4 \Omega}+\frac{1}{6 \Omega} \\ & \therefore \mathrm{R}_{\mathrm{p}}=\frac{12}{11} \Omega=1 \cdot 09 \Omega \end{aligned} \]