Wikimore

Summary

Description

English: Diagram showing a voltage waveform and the corresponding power waveform (dissipated by a resistive load).

The power is zero when the voltage is zero. Otherwise, the power waveform is always positive, as the resistor can only dissipate energy; it cannot supply energy to the circuit. In other words, the resistor outputs power regardless of whether the voltage is positive or negative.

The RMS voltage is shown by the blue line. $V_{\mathrm {rms} }={\frac {V_{\mathrm {pk} }}{\sqrt {2}}}$
The peak power is shown by the red line. $P_{\mathrm {pk} }={\frac {{V_{\mathrm {pk} }}^{2}}{R}}$
The average power is shown by the green line. $P_{\mathrm {avg} }={\frac {P_{\mathrm {pk} }}{2}}={\frac {{V_{\mathrm {rms} }}^{2}}{R}}$

Date

25 April 2016

Source

Own work

Author

Omegatron

SVG development

The SVG code is valid.

This plot was created with Matplotlib.

Category:Valid SVG created with Matplotlib code#RMS%20voltage%20average%20power.svg

Source code

Python code

Source code

import matplotlib.pyplot as plt
from numpy import sin, pi, sqrt, mean, amax, linspace

t = linspace(0, 1.5, 1000)
sig = sin(2*pi*t)
Vrms = 1/sqrt(2)
power = sig**2  # R = 1 ohm
Ppeak = amax(power)
Pavg = mean(power[t < 1])

plt.figure()
plt.subplot(2, 1, 1)
plt.plot(t, sig, color='0.2', lw=1.5)
plt.axhline(Vrms, color='blue', ls='-', lw=1.2, alpha=0.8)
plt.ylabel('Voltage [V]')
plt.margins(0, 0.1)
plt.xticks(linspace(0, 1.5, 7))
plt.yticks([-1, -0.5, 0, 0.5, 1, Vrms])
plt.grid(True, color='0.2', linestyle=':')

plt.subplot(2, 1, 2)
plt.plot(t, power, color='0.2', lw=1.5)
plt.axhline(Ppeak, color='red', ls='-', lw=1.2, alpha=0.8)
plt.axhline(Pavg, color='green', ls='-', lw=1.2, alpha=0.8)
plt.xlabel('Time [s]')
plt.ylabel('Power [W]')
plt.margins(0, 0.1)
plt.ylim(-1.2, 1.2)
plt.xticks(linspace(0, 1.5, 7))
plt.grid(True, color='0.2', linestyle=':')

plt.tight_layout()
plt.savefig('RMS voltage vs average power.svg')

Licensing

I, the copyright holder of this work, hereby publish it under the following license:

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You are free:

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to remix – to adapt the work

Under the following conditions:

attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
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Category:CC-BY-SA-4.0#RMS%20voltage%20average%20power.svg

Category:Self-published work