JEE Mains · Physics · STD 12 -Alternating current
- JEE Mains 2021
- Medium
- Numerical
A transmitting station releases waves of wavelength \(960\, m\). A capacitor of \(2.56\, \mu F\) is used in the resonant circuit. The self inductance of coil necessary for resonance is ............. \(-\times 10^{-8} H\)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(D) \(10\)
Step-by-step Solution
Detailed explanation
\(\lambda=960 m\)
\(C =2.56 \mu F =2.56 \times 10^{-6} F\)
\(c=3 \times 10^{8} m / s\)
\(L =?\)
Now at resonance, \(\omega_{0}=\frac{1}{\sqrt{L C}}\)
[Resoant frequency]
\(2 \pi f _{0}=\frac{1}{\sqrt{ LC }}\)
On substituting \(f _{0}=\frac{ c }{\lambda},\) we have \(2 \pi \frac{ c }{\lambda}=\frac{1}{\sqrt{ LC }}\)
Squaring both sides : \(4 \pi^{2} \frac{ c ^{2}}{\lambda^{2}}=\frac{1}{ LC }\)
\(=\frac{4 \times 10 \times\left(3 \times 10^{8}\right)^{2}}{(960)^{2}}=\frac{1}{ L \times 2.56 \times 10^{-6}}\)
\(\Rightarrow \frac{1}{L}=\frac{4 \times 10 \times 9 \times 10^{16} \times 2.56 \times 10^{-6}}{960 \times 960}\)
\(\Rightarrow L =10 \times 10^{-8} H\)
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