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JEE Main 20199 JanuaryEvening Shift
Exam
JEE Main
Year
2019
Date
9 January
Shift
Evening Shift
Subject
Physics
Chapter
Communication System

JEE Main 2019 · 9 January · Evening Shift · Physics · Communication System

In a communication system operating at wavelength 800nm, only one...

In a communication system operating at wavelength 800nm,800nm, only one percent of source frequency is available as signal bandwidth. The number of channels accommodated for transmitting TVTV signals of band width 6MHz6MHz are (Take velocity of light c=3×108m/s,h=6.6×10−34J−sc = 3 \times {10}^{8}m / s, h = 6.6 \times {10}^{- 34}J-s )

Options

  1. A6.25×1056.25 \times {10}^{5}
  2. B4.87×1054.87 \times {10}^{5}
  3. C3.75×1063.75 \times {10}^{6}
  4. D3.86×1063.86 \times {10}^{6}

Correct answer

A. 6.25×1056.25 \times {10}^{5}

Step-by-step solution

Available signal width =1100×cλ= \dfrac{1}{100} \times \dfrac{c}{\lambda}

=1100×3×108800×10−9Hz=3.75×1012Hz= \dfrac{1}{100} \times \dfrac{3 \times {10}^{8}}{800 \times {10}^{- 9}}Hz = 3.75 \times {10}^{12}Hz

Number of available channels =3.75×10126×106= \dfrac{3.75 \times {10}^{12}}{6 \times {10}^{6}}

=6.25×105= 6.25 \times {10}^{5}
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