$A$ $p-n$ junction diode cannot be used

The frequency response curve of an $RC$ coupled amplifier is shown in the figure. The bandwidth of the amplifier will be

The voltage gain of the following amplifier is

The energy of a photon of sodium light $(\lambda = 589 \text{ nm})$ is equal to the band gap of a semiconductor. Find the minimum energy $E$ in $eV$ required to create an electron-hole pair.

The negative feedback in an amplifier

Two amplifiers are connected one after the other in series (cascade). The first amplifier has a voltage gain of $10$ and the second has a voltage gain of $20$. If the input signal is $0.01\, V$,the output $ac$ signal will be........$V$.