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An ideal choke takes a current of 8 A when connected to an AC source of 100 V and 50 Hz. A pure resistor under the same conditions takes a current of 10 A. If two are connected in series to an AC supply of 100 V and 40 Hz, then the current in the series combination of above resistor and inductor is:

Option: 1

10 A


Option: 2

5 A


Option: 3

5 \sqrt{2} \mathrm{~A}


Option: 4

10 \sqrt{2} \mathrm{~A}


Answers (1)

best_answer

\mathrm{X}_{\mathrm{L}}=\frac{100}{8} \Omega=12.5 \Omega  with 50 Hz frequency and with 40 Hz frequency

\mathrm{ \mathrm{X}_{\mathrm{L}}^{\prime}=12.5 \times \frac{40}{50}=10 \Omega \quad\left[\right. as \left.\mathrm{X}_{\mathrm{L}} \propto \omega\right]}
\mathrm{ \begin{aligned} & \mathrm{R}=\frac{100}{10}=10 \Omega \\ & \therefore \quad \mathrm{Z}=\sqrt{\mathrm{R}^2+\left(\mathrm{X}_{\mathrm{L}}^{\prime}\right)^2}=10 \sqrt{2} \Omega \\ & \quad \mathrm{I}=\frac{100}{10 \sqrt{2}}=5 \sqrt{2} \mathrm{~A} \end{aligned}}

                       

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