Why is a resistor used as a load in rectifier?
A rectifier suggests that you are referring to a power supply, and that the load would never be just a resistance – it would waste energy. There is more to that.
In many cases, it is used to represent the current. There may be no real resistance.
In some cases, when the filter capacitor is of high value, a bleed resistor serving as a load to discharge the cap is needed to quickly discharge the large load from the cap after power failure, avoiding subsequent shocks.
An r load simply simplifies the operation of a rectifier. Since the current can be derived from the simple ohms law. It makes the job easier to understand.
Since you do not have to deal with voltage spikes, return diodes, etc., the load can actually be combined.
Such as rl, RC, r, l, c or rlc. In such cases, as in the case of RLC, depreciation will have to be considered. In the case of rl or RC, there will be a reverse voltage of the capacitor or inductance which will try to return the power supply. So all these complex cases are there.
The load rectifier is the simplest case and does not deal with any of these problems. Most novice level books would have a rectifier with r charge.
Well, practically, it will be a device or an IC that will clean / reduce / increase or use as such the power of the rectifier, but theoretically, it can be anything that has impedance.
For example, for a DC power adapter, a first-stage rectifier (after step-down transformer) converts the DC voltage supply voltage to 20 V (or something else, totally dependent on the design and requirements, as many AC components as possible), possibly save energy for burst operations and even in the event of a short-circuit, reverse polarity or even overload protection, the third floor changes the levels. Voltage as needed.
All these stages, whether combined or not, will have input impedance available at the output of the rectifier and will ultimately decide the current flowing through these output terminals.
Resistance is the simplest case of impedance.