Question

two electric bulb rated as 100 watt , 200 volt and 40 watt,220 volt calculate there resistance

Answer 1

Dear Student,

$$\begin{gathered} {\mathrm{P}}_1=100\mathrm{W} \\ {\mathrm{V}}_1=200\mathrm{V} \\ {\mathrm{P}}_2=40\mathrm{W} \\ {\mathrm{V}}_2=220\mathrm{V} \\ \mathrm{P}=\frac{{\mathrm{V}}^2}{\mathrm{R}} \\ \mathrm{R}=\frac{{\mathrm{V}}^2}{\mathrm{P}} \\ {\mathrm{R}}_1=\frac{{{\mathrm{V}}_1}^2}{{\mathrm{P}}_1} \\ {\mathrm{R}}_1=\frac{{\left(200\right)}^2}{100}=\frac{40000}{100} \\ {\mathrm{R}}_1=400\mathrm{ohm} \\ {\mathrm{R}}_2=\frac{{{\mathrm{V}}_2}^2}{{\mathrm{P}}_2} \\ {\mathrm{R}}_2=\frac{{\left(220\right)}^2}{40}=\frac{48400}{40} \\ {\mathrm{R}}_2=1210\mathrm{ohm} \end{gathered}$$