Question

An electrical device which offers a low resistance to the current in one direction but a high resistance to the current in opposite direction is:
A. Current amplifier
B. Oscillator
C. Power amplifier
D. Rectifier

Answer 1

Hint: The phenomenon of offering low resistance to current in one direction but a high resistance to the current in the opposite can be related to a device which works on the AC signals. That device allows the positive part of the signal to pass through it but blocks the negative part could be the answer to the question.

Complete answer:
We are asked for an electrical device which offers a low resistance to the current in one direction but a high resistance to the current in the opposite direction. The answer to this question is the rectifier.

The basic working principle of a rectifier is to block the flow of current which is in the negative direction but will allow the current in positive direction to pass through it. This property allows the rectifier to convert an AC signal into DC signal since the rectifier removes the negative part of the signal with only the positive part as the output.
The image shows a bridge rectifier which performs full wave rectification. As we can see, the input signal has voltage in both positive and negative direction but the output signal has only positive values of voltage. This means that the rectifier has prevented the flow in negative or opposite direction by turning negative voltages into positive voltages.

Hence, based on the above discussion, the correct answer is option D.

Additional information:
The purpose of an amplifier is to amplify the current or voltage signal passing through it by increasing the amplitude of the incoming signal.
The purpose of an oscillator is opposite to that of a rectifier. As the name implies, the oscillator converts a DC signal into AC signal oscillations.

Note:
It should be noted that the output of the rectifier is unidirectional but still there are variations in the value of the signal though the negative part has been removed. In order to make the signal a constant DC signal, we make use of different types of filters which help accomplish this task.