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 receiver is $10^{-x} \, W$. The value of $x$ is ....... .
$\left[\right.$ Gain in $\left. dB =10 \log _{10}\left(\frac{ P _{0}}{ P _{i}}\right)\right]$
JEE MAIN 2021, Diffcult
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