Finding the Frequency from the Wavelength of Light

The frequency of light is related to the wavelength of light in a very simple way. The spectrometer can be used to examine the light from the LED, and to estimate the peak wavelength of the light emitted by the LED. But we prefer to have the frequency of the peak intensity of the light emitted by the LED. The wavelength is related to the frequency of light by , where c is the speed of light (3 x 10⁸ m/s) and is the wavelength of light read from the spectrometer (in units of nanometers or 10^-9 meters). Suppose you observed the red LED through the spectrometer, and found that the LED emits a range in colors with maximum intensity corresponding to a wavelength as read from the spectrometer of = 660 nm or 660 x 10^-9 m. The corresponding frequency at which the red LED emits most of its light is  or 4.55 x 10¹⁴ Hertz. The unit for one cycle of a wave each second (cycle per second) is a Hertz.