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An electrical bulb rated 220 \mathrm{~V}, 100 \mathrm{~W}, is connected in series with another bulb rated 220 \mathrm{~V}, 60 \mathrm{~W}. If the voltage across combination is 220 \mathrm{~V}, the power consumed by the 100 \mathrm{~W}bulb will be about____________ \mathrm{~W}

Option: 1

14


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer

Bulb 1

\mathrm{(\left.V_R\right)_1=220 \mathrm{~V} }         \mathrm{\quad R_1=\frac{\left(V_R\right)_1^2}{\left(P_R\right)_1}=484 \Omega }

\mathrm{\left(P_R\right)_1=100 \mathrm{~W}}

 \mathrm{\left ( V_{R1} \right )\&\left ( P_{R2} \right )} are voltage rating and power rating for  the bulb1 respectively

Bulb 2
\mathrm{\left(V_R\right)_2=220 \mathrm{~V} \\ }        \mathrm{\quad R_2=\frac{\left(V_R\right)_2^2}{\left(P_R\right)_2}=\frac{4840}{6} \Omega }

\mathrm{\left(P_R\right)_2=60 \mathrm{~W} }

\mathrm{220 =I\left(R_1+R_2\right) }

        \mathrm{=I\left(484+\frac{4840}{6}\right) }

\mathrm{10 =I\left(22+\frac{220}{6}\right) }

\mathrm{I=\frac{60}{352} \mathrm{~A}}
Power consumed by bulb 1

\mathrm{P =I^2 R_1 }

    \mathrm{=\frac{60 \times 60}{352 \times 352} \times(22 \times 22) }

    \mathrm{=\frac{60 \times 60}{16 \times 16}=\frac{225}{16} }

\mathrm{P \cong 14 \mathrm{~W}}





 

Posted by

shivangi.shekhar

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