【文章內(nèi)容簡介】 4). Aim 2: Find wavelengths for lasersl Apparatus: spectrometer, a piece of paper, ruler, red laser pen, blue laser pen, red and blue goggles.l MethodsGoggle is a kind of light filter and it can avoid the light damaging to the eyes by changing the intensity and spectrum of the through lights. The ways of this aim is similar to the aim 1. First of all, one person used the red laser pen to shot at the diffraction grating and the other person observed the diffraction pattern by wearing a blue goggle. The reason why blue goggle was used to observe the red laser is that it can absorb the red light which will protect the eyes, in the same way, the red goggle was put on to protect the eyes when the blue laser pen was used (5). Then, the position of each fringe was recorded. Next, the distance from the different fringes to the center fringe was read from the ruler and it was recorded at another sheet of paper. Later, using the blue laser pen and wearing the red goggle to repeat the last steps. l ResultsTable 3 shows the experiment data of aim 2 and the wavelength of the red and blue laser gotten from it. Table 3: results of aim 2 ColorOrder(n)y(cm)L(m)Wavelength(nm)red1 2 blue1 2 The wavelength calculated from the second order is smaller than the first order, which can be seen from table 3. Both diffraction patterns of the red laser and blue laser have five bright sections and they symmetry about the center fringe. The bright section and the dark section are alternating with each other. When the bright section got far from the center fringe, it became darker and darker. So the brightness of second order is darker than the first order. l AnalysisTable 4 shows the wavelength of the red light and the blue light from aim 1 and aim 2Table 4: Comparison of the results for aim 1 and aim 2ColorWavelength(nm) from aim 1Wavelength(nm) from aim 2first orderWavelength(nm) from aim 2second orderred blue Two fringe orders of diffraction could be seen in aim 2 and there is a fringe on the sides as well as the back (6). The wavelengths of the red and blue LED calculated from the first order are nm and nm. From the second order, the wavelengths are nm and nm respectively. The results of the two aims are not the same: wavelengths of the red light in aim 2 for the first and second order are smaller than aim 1 while which of the blue light of aim 2 are bigger than aim 1 (8). The values of wavelengths of different orders in aim 2 are different. As the pattern of the first order is brighter than the second order, when marked the position of fringes, it will be more accurate. Thus, the result gotten from the first fringe will be more accurate than the second order and they are different. The different separations also will lead to the different results. If the slit separation bees narrower, the diffraction pattern will bee clearer. On the opposite side, the pattern will bee unclear when the slits separation is wider (7).Aim 3: Find wavelengths for LEDl Apparatus:Spectrometer, LEDs, power supply, black plastic bag, leads.l Methodsi. Connect the powers supply and the socket and let the voltage is the minimum valueii. Connect the Red LED to the power supply and regulate the voltage at a proper value to make the LED shine normally. iii. Let the light of the red LED pass through the empty pen and shot at the spectrometer through the diffraction grating. The diffraction pattern will be more clear when the LED passed through the empty pen as the light was gathered and its intensity was strengthened (9). iv. Observe the diffraction pattern from the viewing hole with the black plastic bag covered the head and the viewing hole (the LED was not bright and not easy to be seen, to reduce the light loss and help view, the black plastic bag was used). v. Take done the position of the center of each fringe.vi. Read the distance from each fringe to the center fringe