An electric lamp is marked ${\rm{60}}\,\,{\rm{W}}$, ${\rm{230}}\,\,{\rm{V}}$. The cost of kilowatt hour of power is ${\rm{Rs }}\,{\rm{1}}{\rm{.25}}$. The cost of using this lamp ${\rm{8}}\,\,{\rm{h}}$ a day for ${\rm{30 }}\,{\rm{days}}$ is

$\begin{array}{*{20}{l}} {{\rm{Rs}}\,\,{\rm{18}}} \end{array}$

$\begin{array}{*{20}{l}} {{\rm{Rs}}\,\,{\rm{10}}} \end{array}$

$\begin{array}{*{20}{l}} {{\rm{Rs}}\,\,{\rm{16}}} \end{array}$

$\begin{array}{*{20}{l}} {{\rm{Rs}}\,\,{\rm{20}}} \end{array}$

JEE PHYSICS MCQ: CURRENT ELECTRICITY

1 Medium

1 of 1

Application +4 | -1

An electric lamp is marked

\mathrm{60}\,\,\mathrm{W}

\mathrm{230}\,\,\mathrm{V}

. The cost of kilowatt hour of power is

\mathrm{Rs }\,\mathrm{1}\mathrm{.25}

. The cost of using this lamp

\mathrm{8}\,\,\mathrm{h}

a day for

\mathrm{30 }\,\mathrm{days}

View answer and explanation

Correct option: C

\begin{array}{llllllllllllllllllll} {\mathrm{Rs}\,\,\mathrm{18}} \end{array}

The correct answer is Rs 18 because the total energy consumed is calculated and then multiplied by the cost per kilowatt-hour.