(Image: Bridge Rectifier configuration)
(Image: Bridge Rectifier with input and output)
A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification. The AC voltage generated is passed through a circuit of four diodes arranged as shown above and emerged converted into a more useful DC output. The Red color indicates that those diodes are in forward bias and the black color indicates that those diodes are in reverse bias. The arrows shows the direction of current flow. Even though the output is rectified, we can see that it contains ripples. At a particular time any of the two diodes will be Forward Biased and the other two will be Reverse Biased, as per the polarity at its Anode or Cathode. This creates two different paths for the current at the output for each cycle. However, the polarity of the nodes are not changing at the Output. Thus we are getting a Fully Rectified waveform at the output. Since there is no positive and negative half cycles, it is DC with ripples.
Image Courtesy: www.globelspec.com