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# Ripple (physics)

In physics, ripples (also known as capillary waves) are surface waves on a liquid with wavelengths so short that the liquid's motion is governed almost entirely by surface tension forces. The wavelength of a ripple must be less than $\lambda_c = 2 \pi \sqrt{ \frac{\gamma}{\rho g}}$

where:

• γ is surface tension
• ρ is liquid density
• g is acceleration due to gravity

For water, λc is found to be 1.7 cm.

## Electrical significance

In electricity, ripple is the alternating current component from a direct current power supply arising from sources within the power supply. Unless otherwise specified, percent ripple is the ratio of the root mean square value of the ripple voltage to the absolute value of the total voltage.

The ripple voltage can be calculated from the following equations:

Full-wave rectification: $V_\mathrm{r} = \frac{I}{2fC}$

Half-wave rectification: $V_\mathrm{r} = \frac{I}{fC}$

where

• 'Vr is the ripple voltage
• I is the current in the circuit
• f is the frequency of the AC-power
• C is the capacitance

## References

N. B. Tufillaro, R. Ramshankar, and J. P. Gollub, Order-disorder transition in capillary ripples, Physical Review Letters 62 (4), 422 (1989).