Question

How does a diode acts as a rectifier.

Answer 1

For an AC source, the input voltage Signal is of form$:-$

With reference to Image $1$

Now if a few diodes are used as shown below, it will transform the AC signal into DC signal, thus acting like rectifiers.

With reference Image $2$ and $3$

Here the diode circuits rectifiers the AC signal and transforms the negative half cycles into positive half cycles.

With reference to Image $4$ and $5$

Here the diode only allows the positive half cycles to pass to $R_L$

and does not let the negative half cycles, giving it a DC form.