Which of the following is used to produce radio waves of constant amplitude?

Select the correct statements from the following:

Consider the following statements:
Statement $(A)$: The resistance of an ideal diode in forward biased condition is zero.
Statement $(B)$: In a half-wave rectifier,the load current flows only for every half cycle of the input signals.
Statement $(C)$: In the breakdown region,a Zener diode behaves as a constant voltage source.

$Ge$ and $Si$ diodes conduct at $0.3 \, V$ and $0.7 \, V$ respectively. In the following figure,if the $Ge$ diode connection is reversed,the value of $V_0$ changes by how many volts?

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.

When a potential difference is applied across,the current passing through: