When white light passes through a glass prism, it spreads out into a band of different colours called the spectrum of light. So, the rays of each colour emerge along different paths and appear distinct. Hence, we get a spectrum of seven different colours.

An emission spectrum is the line pattern formed when an element is excited and gives off energy. An absorption spectrum is formed when white light passes through a cool gas. The gas absorbs certain wavelengths of energy and allows others to pass through.

For example, when you see a red shirt, the shirt is absorbing all the colors of light except for the red color. The frequency of light that we see as red is being reflected and we see that shirt as red.

Although c is now the universal symbol for the speed of light, the most common symbol in the nineteenth century was an upper-case V which Maxwell had started using in 1865. That was the notation adopted by Einstein for his first few papers on relativity from 1905.

First, you will need to make sure you have all the materials to make a spectrum:

1. A cardboard box. It needs to be big enough to tape a CD or DVD on the inner edge.
2. A DVD or CD.
3. 2 business cards (or a 3×5 cards).
4. A cardboard tube.
5. Aluminum tape or aluminum foil and glue.
6. Scissors.
7. Pen or marker.
8. Ruler.

Spectrometry is the measurement of the interactions between light and matter, and the reactions and measurements of radiation intensity and wavelength. In other words, spectrometry is a method of studying and measuring a specific spectrum, and it’s widely used for the spectroscopic analysis of sample materials.

Colors of the Visible Light Spectrum

• Violet – shortest wavelength, around 400-420 nanometers with highest frequency.
• Indigo – 420 – 440 nm.
• Blue – 440 – 490 nm.
• Green – 490 – 570 nm.
• Yellow – 570 – 585 nm.
• Orange – 585 – 620 nm.
• Red – longest wavelength, at around 620 – 780 nanometers with lowest frequency.

A solar symbol is a symbol representing the Sun….Astronomical symbol.

Each wave has two parts; an electric part, and a magnetic part. That’s why light is called Electromagnetic Radiation. The shortest wavelengths of the spectrum are the ultraviolet, x-ray, and gamma radiation. The visible portion is a very small part of the electromagnetic spectrum.

Light color and spectrum is the result of additive color mixing – by varying the relative amounts of each color input, the resulting SPD and chromaticity can be manipulated. Fixed phosphor-converted LEDs (principle behind all white LEDs) use specific phosphor recipe mixes to achieve specific color specs (e.g. 2700K 95 CRI).

Examine different light sources. Hold the spectrum up to a light, putting the viewing port (the paper tube) over your eye and aiming the viewing slit at a light. You should see the full light spectrum, from red to purple.

Creating a spectrum (or “spectroscope”) is an educational and fun activity that allows you to see the different colors that make up a wave of light: red, orange, yellow, green, blue, indigo, and violet.

Record your observations. Record how different light sources look in the spectrum by writing down the light source (such as “candle flame”) then using colored pencils to draw the colors you see. You can also use a camera to take a picture of the spectrum through the viewing port, although this can be a bit tricky.