Color and spectra

Objective: The purpose of this experiment is to collect  the wavelengths for certain gases and to identify an unknown gas. Different elements have their own and special wavelength. In this lab, students apply the concept of constructive interference and use the equation y=Lλ/d, with L is the length from light source to slit, y is the distance between the color of interest to the light source and d is the distance between slits. Student will measure the wavelength of a white light source using a straight filament light bulb first. Next, the wavelength measurements of hydrogen gas is taken. After that, student will measure the wavelength of unknown gas. Based on the wavelength the unknown element has, student has to identify it.



Figure 1: the set up of this experiment

Figure two, the color can be seen from the color filter.

Figure 3: unknown gas that has to be identified.

Data
 White light

Color	y	Average distance(cm)	experimental wavelength(nm)	actual wavelength(nm)
Violet	18.00-22.50 ± 0.50	20.25 ± 0.50	405 ± 10	415
Blue	22.50-24.20 ± 0.50	23.35 ± 0.50	467 ± 10	463
Green	24.20-27.50 ± 0.50	25.85 ± 0.50	517 ± 10	533
Yellow	27.50-30.00 ± 0.50	28.75 ± 0.50	575 ± 10	580
Red	30.00-38.50 ± 0.50	34.25 ± 0.50	685 ± 10	685

Hydrogen

Color	y	Experimental wavelength(nm)	Adjusted experimental wavelength(nm)	Actual wavelength(nm)
Violet	19.90 ± 0.50	398 ± 10	405 ± 23	410
Green	22.10 ± 0.50	442 ± 10	449 ± 23	434
Yellow	27.00 ± 0.50	540 ± 10	545 ± 23	486
Red	31.60 ± 0.50	632 ± 10	636 ± 23	656

Unknown gas

Color	Y(cm)	Experimental wavelength(nm)	Adjusted experimental wavelength(nm)
Violet	23.40 ± 0.50	468 ± 10	474 ± 23
Green	27.20 ± 0.50	544 ± 10	549 ± 23
Yellow	29.90 ± 0.50	598 ± 10	602 ± 23
Orange	31.10 ± 0.50	622 ± 10	626 ± 23
Red	33.00 ± 0.50	660 ± 10	663 ± 23

Conclusion: In the white light source, wavelengths of red, yellow, green, blue, and violent are measured. This is because white light is composed of all these colors. For hydrogen gas, four wavelength colors are recorded, they are violent, green, yellow, and red. This is because hydrogen gas only have these four colors. For the unknown gas, five colors of violent, green, yellow, orange, and red are seen and their wavelengths are collected. Based on the colors and wavelength, the unknown number 4 gas is determined to be neon. The actual color of neon gas is pink, blue, green, and red. Although some of the colors are hard to detected with naked eye, the result is quite accurate. The wavelength uncertainty is low, which means that this experiment can accurately measure the wavelength of the color emitted from the gas.