The electrical circuit used to get smooth DC output from a rectifier circuit is called:
(A) Filter
(B) Oscillator
(C) Logic gates
(D) Amplifier

Hint: The electrical circuit used to get a smooth DC Output from a circuit is known as a rectifier circuit. In a rectifier, a diode is used to get a DC output. Such a type of rectifier is known as a half-wave rectifier. To make a full-wave rectifier, we use two diodes instead of one.

Complete step by step answer:
Rectifier circuit converts a sinusoidal AC voltage into its corresponding pulsating DC. But apart from the DC component, this pulsating output will have unwanted AC components like the supply frequency along with the harmonics. To obtain a smooth DC output, these unwanted AC components must be removed.
This is achieved using Filter circuits. In signal processing, a filter is a device or process that removes some unwanted components or features from a signal. Filter circuits can be a series Inductor filter circuit or a capacitor filter circuit. Filters are used because if the rectifier output is smooth and steady and then passed on as the supply voltage, the operation of the circuit becomes better.
Hence (A) is the correct option.

Note: We got our answer in the first option so we didn’t go further. But it’s always useful to analyse all the options before marking it. An oscillator is a circuit that produces a continuous, repeated, alternating waveform without any input. So the oscillator does the opposite of what we want to find out. It converts a DC signal into an alternating waveform. Logic gates are the building blocks of all digital systems and they are used to implement propositional logic. They work on binary inputs and give binary outputs. The amplifier is a device used to increase the voltage, current, or power of a signal. Hence we can see why the other options cannot be correct.