Discussion Forum



1)

A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 picofarad in parallel witha load resistance 100 kΩ . Find the maximum modulated frequency which coud be dectected by it


A) 10.62 MHz

B) 10.62 kHz

C) 5.31 MHz

D) 5.31kHz

Answer:

Option B

Explanation:

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$\tau= RC= 100\times 10^{3}\times250\times 10^{-12}s$

   = 2.5 x 10-5 s

  The higher frequency which can be  detected with tolerable  distortion is

$f=\frac{1}{2\pi m_{a}RC}$

    $=\frac{1}{2\pi \times0.6\times2.5\times 10^{-5}}Hz$

   $=\frac{100\times 10^{4}}{25 \times1.2\pi }Hz$

     $=\frac{4}{ 1.2\pi }\times 10^{4}Hz$

   = 10.61 kHz