JEE Mains · Physics · STD 12 -Alternating current
- JEE Mains 2021
- Hard
- MCQ
Find the peak current and resonant frequency of the following circuit (as shown in figure).

Pick an option to check your answer.
Answer & Solution
Correct Answer
(A) \(0.2\, A\) and \(50 \,Hz\)
Step-by-step Solution
Detailed explanation
as given \(z=\sqrt{\left(x_{L}-x_{C}\right)^{2}+R^{2}}\)
\(x _{ L }=\omega_{ L }=100 \times 100 \times 10^{-3}=10 \, \Omega\)
\(x _{ C }=\frac{1}{\omega_{ C }}=\frac{1}{100 \times 100 \times 10^{-6}}=10\, \Omega\)
\(z=\sqrt{(10-100)^{2}+R^{2}}=\sqrt{90^{2}+120^{2}}\)
\(=30 \times 5=150\, \Omega\)
\(i _{ peal }=\frac{\Delta v }{ z }=\frac{30}{150}=\frac{1}{5} amp =0.2\,amp\)
And For resonant frequency
\(\Rightarrow \omega L =\frac{1}{\omega C } \Rightarrow \omega^{2}=\frac{1}{ LC } \Rightarrow \omega=\frac{1}{\sqrt{ LC }}\)
And \(f=\frac{1}{2 \pi \sqrt{L C}} \Rightarrow \frac{1}{2 \pi \sqrt{100 \times 10^{-3} \times 100 \times 10^{-6}}}\)
\(=\frac{100 \sqrt{10}}{2 \pi}=\frac{100 \pi}{2 \pi}=50\, Hz\)
as \(\sqrt{10} \approx \pi\)
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