364385.fig.001a
(a) 22 Hz sine
364385.fig.001b
(b) Spectrum of sine wave
364385.fig.001c
(c) 22 Hz triangle
364385.fig.001d
(d) Spectrum of triangle wave
364385.fig.001e
(e) 22 Hz 50% duty cycle square
364385.fig.001f
(f) Spectrum of square wave
Figure 1: (a), (c), and (e) are the luminance figures of an LED measured by a Lutron LX-102 light meter. Their corresponding frequency representations are given in (b), (d), and (f), respectively. The spectrum of the square wave strictly adheres to theory, that is, a peak demonstrated at fundamental frequency 𝑓 as well as a peak at the 3 𝑓 harmonic. The sine wave and the triangle wave do not. They have weak harmonics that should not exist at 2 𝑓 . However, these harmonics should not affect the result, since their strength are one tenth that of the fundamental frequency.