Figure 4 Measure the voltage across a zener diode with a digital multimeter. You can use the circuits in figures 2 and 3 to test LEDs, regardless of their color. Place the forward-biased LED you would ...

The increasing applications of LED ... using a high speed (il)luminance measurement device, or, for instance, a colorimeter, based on the implementation of the measurement devices and samples being ...

There’s a little more to it, of course; the method is based on measuring the voltage at which LEDs of various wavelengths ... room with adapted eyes, or by using an opaque tube to block out ...

You can use a multimeter with capacitance-measurement capability to measure the length of wire or cable to an open circuit. The capacitance of a pair of wires (or a wire to a shield) is directly ...

So, let’s get back to our task. It seems pretty easy: Take an LED (let's start with red), pass its light through the spectrometer, and use that to measure the exact wavelength of light.