A signal of 0 . 1 kW is transmitted in a cable. The attenuation of cable is - 5 dB per km and cable length is 20 km . The power received at the receiver is 10 - x W . The value of x is _________. [Gain in dB = 10 log 10 P O P i ]

Step-by-step solution

Sound level decreases by 5   dB every km so, sound level decreased in 20   km = 100   dB β 2 - β 1 = 10   log 10 I 2 I 1 - 100 = 10   log 10 I 2 I 1 ⇒ I 1 I 2 = 10 10 I 2 = 10 - 10 I 1 ⇒ P 2 = 10 - 10 P 1 = 10 - 8   W x = 8