Question

The inductance L (in mH) of the coil which is to be connected in series with a capacitor of 0.3 pF to get an oscillatory resonance frequency of 1 MHz is.

• A. 8.44mH
• B. 84.4mH
• C. 844mH
• D. 8440mH

Answer 1

The correct option is B 84.4mH

$f=\frac{1}{2\pi }\frac{1}{\sqrt{LC}};$
$L=\frac{1}{4{\pi }^2{f}^{2}C}$
$L=\frac{1}{4{\pi }^2\times {10}^{+12}\times 0.3\times {10}^{-12}}$
$=\frac{1}{12}=0.0844$
$=84.4\times {10}^{-3}$
= 84.4 mH