experiment 13 meausre the wavelengh

Purpose:

the purpose of this experiment is to measure the wavelength of different light source.

equipment:

white light, unknown gas source, hydrgen gas source, ruler, diffraction glass.

Experiment and Data Collection:

first of all, we need to set up the equipment, we use two ruler, one is 2 meters, and another one is 1 meter long, fix them in right angle at the end of the two rulers. then put the light source in the corner of the two rulers, put a diffraction plastic card in oneside of the 2 meters ruler, then read the diffraction light through the diffraction plastic card in different color on the one meter ruler. the experiment has three part, first part light source is white light, second light source is unknow and we need to find the unknow of the light through the calculation, and the third is hydrgen light source.

we get the distance from the diffraction plastic card to the center of the white light L = 2.02 m

we get the slits of the plastic card is d = 1.76*10^-6 m

for all the three part of the experiment, the two data above are the same.

then we use equation formula λ= d*D/(d^2+D^2)^1/2, to calculate the wavelength of the light source in different color.

First part white light source:

Color	Distance /m	Wavelength /m
Violet	0.478	4.05*10^-7
Blue	0.569	4.77*10^-7
Green	0.63	5.24*10^-7
Yellow	0.64	5.32*10^-7
Orange	0.679	5.61*10^-7
Red	0.804	6.51*10^-7

Second part unknow light source:

Color	Distance /m	Wavelength /m
Violet	0.474	4.02*10^-7
Green	0.593	4.96*10^-7
Yellow	0.64	5.32*10^-7
Orange	0.67	5.54*10^-7
Red	0.79	6.41*10^-7

after we compare the wavelenght to the spectru table, we consider our unknow is mercury.

then we need to find the calibration equation of our equipment to reduce the error for our third part experiment, we get the actual wavelengh of the mercury for three color, then make a graph that actual wavelengh vs the experiment value of the wavelengh.

Color	Y /nm	X /nm
Violet	430	402
Green	548	496
Yellow	577	532

from the graph we get the calibration equation is y = 1.1559x - 32.641.

Third Part:

the third part we need to measure the hydrgen gas light wavelength, then we need to calibrate.

Color	D /m	Wavelength /m	After calibrate /m	Wavelength actual/m
Violet	0.48	4.06*10^-7	4.37*10^-7	4.34*10^-7
blue	0.588	4.92*10^-7	5.36*10^-7	4.86*10^-7
red	0.742	6.07*10^-7	6.69*10^-7	6.56*10^-7

after the calibration, we compare he wavelength to the actual wavelength, the Violent, and red color compare to the actual value are very close, but the second blue color compare to the actual wavelength, there are about 50 nm off.

Conclusion:

from thsi experiment ,we are successful find the wavelength of different light source in different color, but still have some error percent.