How Smoothing Works
How Smoothing Works
- A rectified voltage is one-way, but it still rises and falls. A capacitor stores charge and supports the output between peaks.
The rectifier and capacitor have different jobs
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The four diodes first make a one-way voltage. The large capacitor then reduces the remaining variation. Rectification must happen before smoothing.
Connect the capacitor across the load
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- The capacitor is in parallel with the load, so both have the same potential difference.
- Near a rectified peak, the capacitor charges quickly.
- When the input falls, the capacitor discharges through the load and slows the fall in output voltage.
- At the next peak, it charges again. The repeated small rise and fall is called ripple.
- Larger capacitance or larger load resistance gives slower discharge and smaller ripple.
- For the same input frequency, full-wave rectification recharges the capacitor twice as often as half-wave rectification. With the same load and capacitance, this leaves less time to discharge and gives smaller ripple.
Increase either capacitance or load resistance → increase the time constant → reduce ripple.
Your turnrelationship check
The capacitance is doubled while the load resistance and input stay fixed. State the changes to discharge rate and ripple size.
Show worked answer
Discharge becomes slower because the time constant is larger. The voltage falls less between peaks, so ripple becomes smaller.