Full Wave Rectifier:
A full wave rectifier is an electronic circuit that converts alternating current (AC) to pulsating direct current (DC). It is commonly used in power supplies and other electronic devices to convert the AC input voltage into a DC output voltage.

Working Principle:
The full wave rectifier uses a bridge rectifier circuit, which consists of four diodes arranged in a bridge configuration. The AC input voltage is applied to the two ends of the bridge, and the output is taken from the remaining two ends. The diodes are arranged in such a way that during the positive half cycle of the input AC voltage, the current flows through two diodes in one direction, and during the negative half cycle, it flows through the other two diodes in the opposite direction.

Pulsating Unidirectional Voltage:
The output of a full wave rectifier is a pulsating unidirectional voltage. This means that although the output voltage has a constant polarity (unidirectional), it still contains AC components and is not pure DC. During each half cycle of the input AC voltage, two diodes conduct and allow the current to flow through the load resistor in one direction. As a result, the output voltage rises to the peak value of the AC input voltage. However, during the other half cycle, the other two diodes conduct and the current flows in the opposite direction through the load resistor. This causes the output voltage to drop to zero.

DC Voltage:
Although the output of a full wave rectifier is not a pure DC voltage, it can be further filtered using a capacitor or other smoothing techniques to convert it into a DC voltage. The capacitor acts as a filter and smoothens out the variations in the output voltage, resulting in a nearly constant DC voltage.

Conclusion:
In conclusion, the output from a full wave rectifier is a pulsating unidirectional voltage. It has a constant polarity but contains AC components. However, by further filtering the output, it can be converted into a pure DC voltage.