PHYSICS COURSE NAME LAB x V0.61 LAB EXERCISE COTR - L1 DIFFRACTION AND INTERFERENCE OF LIGHT Lab format: This lab exercise is performed with the lab kit. Relationship to theory: This lab exercise explores the diffraction and Interference of light using a laser and various slit configurations including a diffraction grating. OBJECTIVES The student will investigate the wave properties of light using a solid state laser, various slit combinations, and a diffraction grating. EQUIPMENT LIST Lab Kit Solid State Laser 2 Single edge razor blades Cornell Slit-film 500 or 600 lines/mm diffraction-grating 4 Bulldog Paper Clips Callipers Flat Mirror (front silvered would be best) Student Supplied Solid Table that won’t wiggle White metric graph paper (5 to 10 sheets) Masking tape Measuring Tape, ruler, and/or metre stick Level (if not part of the laser) Shims (slips of paper and/or cardboard) Sharp pencil or mechanical pencil for sketching Figure 01: Lab Equipment Creative Commons Attribution 3.0 Unported License 1 PHYSICS COURSE NAME LAB x INTRODUCTION In this experiment, we will investigate the wave nature of light by stuΔing two effects -- diffraction and interference. We will use these two effects to predict patterns given by single and multiple slits, and calculate the slit spacing of a diffraction grating. Since we know the wavelength of the laser's red light very precisely, we will use this to verify our calculations. WARNINGS Caution: Don't shine the intense laser light in anyone's eyes! Continuous exposure could cause irreversible eye damage. Don't get fingerprints on the Cornell Slit-film, or the Diffraction grating or their function could be compromised. Handle them only by their edges. DO NOT clean them with Windex or a similar product because the ammonia dissolves the film gelatine! If you must clean them use a dry soft cotton cloth and don’t rub too hard. The Cornell Slit-Film is glass and will break if dropped. Handle it carefully! THEORY A. INTERFERENCE Electromagnetic waves act as a series of plane waves of the form: E t , x E0 sin 2 ft kx ; EQ L1.01 Where E is the amplitude of the electric field in volts/m at time t at some distance x, Eo is the peak amplitude, f is the frequency of the wave in hertz (f = 1/T), k is the wave number (k= 2π/λ) which is the phase angle in radians per metre and λ is the wavelength in metres (where λ= c/f = cT) and c is celerity, the speed of light. Like other electric and magnetic fields, light waves combine according to the principle of linear superposition. If two light waves meet at some point at the same time then the electric field at that point will be the vector sum of the individual fields. Their amplitudes add algebraically and the waves may interfere: 1) Destructive Interference: If two equal amplitude (sine) waves meet exactly out of phase by an optical path difference of ½λ then they cancel and the net electric field there is zero. 2) Constructive Interference: If two equal amplitude waves meet exactly in phase, then they combine and give a wave of double amplitude. B. DIFFRACTION When parallel light waves pass a barrier, some light seems to flow into the geometric shadow. This behaviour is called diffraction. It means that light can bend around corners and spread-out when Creative Commons Attribution 3.0 Unported License 2 PHYSICS COURSE NAME LAB x passing through small openings. But the wavelength of light is very short, so diffraction is noticeable only when light passes through extremely narrow slits, or sharply defined obstacles. A laser is used so that these faint interference and diffraction effects become visible. It provides a very bright plane wave-train that appears to come from infinity, having one pure colour of constant phase (coherence) which keeps the pattern fixed in space. The laser in the lab kit will be a solid state laser that emits light with a wavelength between about 630 nm to 650 nm. The one used during the writing of this lab exercise was a Jobmate Laser Level (model 57-5302-8) purchased from Canadian Tire. The one in your lab kit will be similar, but most likely will not be identical. The lens that creates the line for the laser level has been removed so that this laser emits a beam instead of a line. The one in your lab kit should not require this modification or will allow you to set it to a beam. Huygen's Construction Principle: This model is used to show the wave nature of diffraction. If we place a row of point sources along a wavefront, then each point gives rise to a circular wavelet that adds to the other wavelets to produce the familiar parallel wavefront. See Figure 02. We only use the forward facing halves of the circular wavelets: the back halves are ignored since they are going in the opposite direction (and would imply the wavefront was travelling the other way). Figure 02: A Plane Wave as a Row of Expanding Circles Figure 03: Half Barrier Diffraction comparing Huygens Construction to a Ripple Tank Photo In Figure 03 where the light-wave meets a sharp half barrier, the edge of the wavefront passing the barrier acts as a point source sending circular patterns into the shadow behind the barrier. Creative Commons Attribution 3.0 Unported License 3 PHYSICS COURSE NAME LAB x The light is bright in the central region. But on closer inspection a variation in brightness can be observed where the parallel waves interfere with the circular waves and give a pattern of fine lines. This effect can be seen by shining a laser beam on the edge of a razor blade. C. Single-Slit Diffraction Figure 04: Single Slit Diffraction Pattern A pattern appears when we send a plane wave through a small slit of width w, which we call a diffraction pattern. Let’s find the distance y from the centre of the slit to the first minimum in the pattern. To do this, light from the centre must destructively interfere with light from the edge of the slit. The distance travelled by these two waves must differ by exactly half a wavelength (λ/2). Referring to Figure 04, since the slit width w is very small, and the distance r from slit to screen is very large in comparison, then we can assume the ray paths AQ, CQ and DQ are parallel. Thus we can draw a line AB perpendicular to the ray paths to create a similar triangle ABC to triangle CPQ, in which the angle is the same. Then, to relate and λ at the first minima, from the small triangle we get: sin /2 ; w/2 w and thus wsin ; EQ L1.02 EQ L1.03 If we increase path difference CB by nλ/2, the general form is: n wsin ; {where n is an integer} EQ L1.04 Here, a minima occurs where n is odd, a maxima where n is even. Creative Commons Attribution 3.0 Unported License 4 PHYSICS COURSE NAME LAB x 2n ;(n 1, 2,3,...) for minima 2 2n 1 ;(n 1, 2,3,...) for maxima w sin 2 w sin EQ L1.05 EQ L1.06 Continuing to find the distance y along the screen to the first minima when r y , then tan sin . Using the big triangle CPQ: tan y r ; so for sufficiently small y r tan r sin r w EQ L1.07 thus for the first minima: y r ; w EQ L1.08a For the second minima: y 2r ; w EQ L1.08b And for the nth minima: y nr ; n 1, 2,3,... ; w EQ L1.08c Notice that the differences between adjacent minima (and indeed the maxima) are all r so if we w measure the difference between one minima (or maxima) and the next we will have: y yn yn 1 n r r r r n 1 n n 1 ; w w w w EQ L1.09 This will allow us an easier way to make accurate measurements of the patterns produced. The intensity, I, (advanced: see textbook) can be given by: I I0 where sin 2 / 2 / 2 2 w sin 2 ; . Creative Commons Attribution 3.0 Unported License EQ L1.10 EQ L1.11 5 PHYSICS COURSE NAME LAB x D. Double-Slit Interference and Diffraction Pattern Figure 05: Double Slit Diffraction Pattern For the double-slit, like the single-slit we get minima and maxima when the path difference is nλ: n d sin ; EQ L1.12 where d is the centre to centre slit separation and tan y y tan 1 ; r r Using the same approximation for small as above, we can show that: y nr ; d EQ L1.13a r ; d EQ L1.13b and that y Using wave superposition, the relative intensity I of the pattern compared to the central maximum intensity ( I 0 ) is: I 4I0 sin 2 / 2 / 2 2 1 cos 2 ; 2 EQ L1.14 where α is the phase difference of the slit width: and δ is the phase difference between slits: 2 w sin 2 d sin Creative Commons Attribution 3.0 Unported License EQ L1.15 EQ L1.16 6 PHYSICS COURSE NAME LAB x Figure 06: Combined Single Slit and Double Slit Wave Pattern Shown at Top, Separate Components Below. This means that there are really two underlying wave patterns competing; the single-slit pattern (see Figure 04) and a double-slit pattern that is modulated by the single-slit pattern. Shown in Figure 06 is a graph (done with Richard Hewko's PLOT2D program) which plots the intensity equations for a double-slit pattern with width w = 8λ and separation d = 26λ. Io was assigned a value of 1 to give relative intensity along the y-axis. The combined wave pattern is shown at the top then the two underlying wave patterns are separated out and shown below. E. Multiple-Slit Diffraction Patterns Figure 07: Interference Pattern of Equally Spaced Sources Creative Commons Attribution 3.0 Unported License 7 PHYSICS COURSE NAME LAB x For three slits, there is a small secondary maxima between each pair of principal maxima, and the principal maxima are sharper and more intense than those produced by just two slits. For four slits, there are two small secondary maxima between each pair of principal maxima, and their principal maxima are even more narrow and intense. In general, as the number of slits (N) increase, the principal maxima become sharper, with their intensity proportional to N² relative to a single-slit. Secondary maxima become fainter. Diffraction Gratings: When we have hundreds of slits then we have a diffraction grating which gives sharp and precise principal maxima without distracting secondary maxima: these are used in optical instruments like spectrometers. For a diffraction grating, the formula is similar to the double-slit, but with just the distance d between slits required. n d sin ; EQ L1.17 Where d is distance between slits, is the angle of diffraction, and n identifies one of the principal maxima (0,1,2,3...). Here n = 0 identifies the 0th order maxima (which goes straight through), 1 the firstorder principal maxima, 2 the fainter second-order, up to about the third or fourth-order. Usually only 2 or 3 maxima exist. Again, we can show that for sufficiently small : y nr ; d EQ L1.18a r d EQ L1.18b and that y The previous equations all assume the incident beam is perpendicular to the grating: but if it is not, then an error correction is applied: n d sin sin ; EQ L1.19 where is the incident angle. Creative Commons Attribution 3.0 Unported License 8 PHYSICS COURSE NAME LAB x SUMMARY For all the above cases the maxima are determined by the formula: n d sin ; EQ L1.20 Where n represents the order of the bright fringe (0,1,2,3...), and d is the aperture distance (the distance between slits for double-slits & diffraction gratings, and the slit width for a single-slit). For sufficiently small : y r ; d EQ L1.21 PROCEDURE 1) Place the table close to or against the wall you intend to use. Use the carpenter’s level (or, if you are using a laser level, use the levels built into the laser level) and the shims to make sure the table is as level as possible. Also use the shims to make sure the table does not ‘wobble’ when you lean on it. Figure 08: Levels 2) Turn on the laser. Caution: don't shine the intense laser light in anyone's eyes! Place the laser at the end of the table farthest from the wall and make sure it is close to level (if the table top is level then this should not be difficult). Aim it at the wall making sure the laser beam is approximately perpendicular to the wall. 3) Tape the flat mirror to the wall where the laser beam will strike its approximate centre. (Be sure to use masking tape so that you don’t accidentally remove the paint when you remove the mirror. Painter’s masking tape would be best.) 4) You want to adjust the aiming of the laser so that the beam reflects off the mirror and back into the laser. Use the white card to determine where the beam is reflecting. If it is reflecting to the left or right of the laser move it so that the beam is reflecting back in the same vertical plane as the laser is shining in. This is very important for this lab exercise to work properly. Now adjust the laser’s level so the reflected beam shines back into the laser’s aperture. The vertical Creative Commons Attribution 3.0 Unported License 9 PHYSICS COURSE NAME LAB x alignment isn’t as critical as the horizontal alignment, but be as accurate as you can anyway. From now on be careful not to disturb the alignment of the laser. If you accidentally bump it, then repeat steps 3 and 4 to make sure the laser beam is perpendicular to the wall before proceeding. Figure 09: Mirror taped to wall and laser beam re-entering the laser aperture 5) Remove the mirror from the wall and tape a white piece of metric graph paper to the wall in its place so that the laser beam is shining at the approximate middle of the paper near the top. Figure 10: Laser aimed at Graph Paper on the wall Part 1: Half Barrier and Single Slits Note - The images below are provided only to give you an example of what you should see. They should not be used as your data. 6) Place a razor blade into a clip as shown in Figure 11 to create a half barrier and position it in the laser beam so that the razor blade edge blocks about half of the laser beam. Make sure the plane of the razor blade is as close to perpendicular to the laser beam as possible. Notice how a Creative Commons Attribution 3.0 Unported License 10 PHYSICS COURSE NAME LAB x sharp edge will bend light around corners (see Figure 03). Use your pencil to trace the pattern you see on the graph paper noting which side of your sketch is the same as the side the razor blade is on. Why are there dark vertical lines on just one side? Label this tracing “Half Barrier Pattern” Figure 11: Razor blade splitting laser beam Figure 12: Half Barrier Pattern 7) Move the graph paper up a couple of cm and re-tape it to the wall. Mount the second razor blade as before and position the 2 razor blades such that they create a slit. See figure 13. Vary the distance between the 2 razor blades and watch what happens to the pattern. Is this what you expected? When you get a pattern that looks something like figure 14, sketch it. Figure 13: Razor blades forming a single slit Figure 14: Razor Blade Single Slit Pattern 8) Move the graph paper up a few cm and re-tape it to the wall. a. Now position the 0.75 mm single slit on the Cornell Slit-film in the path of the laser beam so that the beam passes through that slit. (See Appendix 1: The Cornell Slit-film to determine which slit pattern you should be using.) You may need to use various thickness books to get correct slit into the path of the laser beam. Now you have two wave patterns, one from each side of the slit, interfering to give distinct red and dark bands as shown in Figure 04. Trace the pattern you see on the graph paper with your pencil and label it “0.75 mm Slit Pattern”. b. What happens to the dark band spacing when you replace the 0.75 mm slit with the 1.5 mm slit? Move the paper up a couple of cm again, trace this pattern, and label it “1.5 mm Slit Pattern”. c. What happens if you replace the 1.5 mm slit with the 0.5 mm slit? Again move the graph paper up a couple cm, trace this pattern, and label it “0.5 mm Slit Pattern”. d. Repeat this process for the 0.25 mm and 0.13 mm slits as well. e. In each case is the central bright fringe twice the width of any other bright fringe in each case? (Figures 15 to 24 give examples of what you should see. Your eye will pick out more detail than these images reveal.) Creative Commons Attribution 3.0 Unported License 11 PHYSICS COURSE NAME LAB x Figure 15: 0.75 mm Single Slit Figure 16: 0.75 mm Single Slit Pattern Figure 17: 1.5 mm Single Slit Figure 18: 1.5 mm Single Slit Pattern Figure 19: 0.5 mm Single Slit Figure 20: 0.5 mm Single Slit Pattern Figure 21: 0.25 mm Single Slit Figure 22: 0.25 mm Single Slit Pattern Figure 23: 0.13 mm Single Slit Figure 24: 0.13 mm Single Slit Pattern Part 2: Multiple Slits Note - Make sure the laser beam is still perpendicular to the wall by repeating steps 3 and 4 if necessary. 9) Tape a new piece of graph paper to the wall so that the laser beam strikes it near the centre top. Creative Commons Attribution 3.0 Unported License 12 PHYSICS COURSE NAME LAB x 10) Place the 0.10 mm slit in the path of the laser beam making sure the slit-film is perpendicular to the beam. You can check this by positioning the slit-film so that the reflected portion of the beam reflects back into the laser aperture. Arrange the graph paper so that the pattern is parallel to one of the horizontal grid lines. Measure the ‘radius’ from the slit-film to the paper. This is ‘r’. Trace the pattern on the graph paper and use the Vernier callipers to measure the distance (Δy) between adjacent dark fringes near the centre of the pattern and record this on the graph paper for later. Label this trace “0.10 mm Slit Pattern”. Compare this pattern to the patterns obtained in Part 1. Figure 25: Equipment Figure 26: 0.10 mm Single Slit Figure 27: 0.10 mm Single Slit Pattern 11) Move the graph paper up a couple of cm, and place the double slit (w = 0.10 mm and d = 0.20 mm) in the path of the laser beam making sure the slide is perpendicular to the beam, and the slits are vertical. Measure the radius from the slit-film to the graph paper. Trace this pattern on the graph paper and measure the distance (Δy) between adjacent dark fringes near the centre of the pattern with the callipers. Label this trace “Double Slit Pattern; w = 0.10 mm; d = 0.20 mm”. Figure 28: Double Slit; w = 0.10 mm; d = 0.20 mm Figure 29: Double Slit; w = 0.10 mm; d = 0.20 mm Pattern 12) Move the graph paper up a couple of cm, and place the double slit (w = 0.10 mm and d = 0.40 mm) in the path of the laser beam making sure the slide is perpendicular to the beam, and the slits are vertical. Measure the radius (r) from the slide to the screen. Trace this pattern on the graph paper and measure the distance (Δy) between adjacent dark fringes near the centre of the pattern with the callipers. Label this trace “Double Slit Pattern; w = 0.10 mm; d = 0.40 mm”. Creative Commons Attribution 3.0 Unported License 13 PHYSICS COURSE NAME LAB x Figure 30: Double Slit; w = 0.10 mm; d = 0.40 mm Figure 31: Double Slit; w = 0.10 mm; d = 0.40 mm Pattern 13) Move the graph paper up a couple cm, and place the double slit (w = 0.10 mm and d = 0.70 mm) in the path of the laser beam making sure the slide is perpendicular to the beam, and the slits are vertical. Measure the radius from the slit-film to the graph paper. Trace this pattern on the graph paper and measure the distance (Δy) between adjacent dark fringes near the centre of the pattern with the callipers. Label this trace “Double Slit Pattern; w = 0.10 mm d = 0.70 mm”. Figure 32: Double Slit; w = 0.10 mm; d = 0.70 mm Figure 33a: Double Slit; w = 0.10 mm; d = 0.70 mm Pattern Figure 33b: Double Slit; w = 0.10 mm; d = 0.70 mm Pattern Detail Note: Be careful to measure the close-spaced double-slit pattern separation, not the wider-spaced single-slit brightness variation pattern: see Figures 05 and 06 and Figure 33b for a picture of the detail. Beware; if you slightly move the laser beam to cover only half of the double-slit, you get just the singleslit pattern. What happens to the pattern when the double-slits are wider apart? You should see a combined single-slit/double-slit pattern as in Figure 06. Also note the detail in Figure 33b. 14) Tape a new piece of graph paper to the wall so that the unimpeded laser beam is centred near the top. Place the 3-slit (w = 0.06 mm and d = 0.13 mm) in the path of the laser beam making sure the slide is perpendicular to the beam, and the slits are vertical. Measure the radius from the slide to the screen. Trace this pattern on the graph paper and measure the distance (Δy) between adjacent dark fringes near the centre of the pattern with the callipers. Label this trace “3-Slit Pattern; w = 0.06 mm d = 0.13 mm”. Creative Commons Attribution 3.0 Unported License 14 PHYSICS COURSE NAME LAB x Figure 34: 3-Slit; w = 0.06 mm; d = 0.13 mm Figure 35: 3-Slit; w = 0.06 mm; d = 0.13 mm Pattern Creative Commons Attribution 3.0 Unported License 15 PHYSICS COURSE NAME LAB x 15) Move the graph paper up a couple of cm, and place the 4-slit slide (w = 0.06 mm and d = 0.13 mm) in the path of the laser beam making sure the slide is perpendicular to the beam, and the slits are vertical. Measure the radius from the slide to the screen. Trace this pattern on the graph paper and measure the distance (Δy) between adjacent dark fringes near the centre of the pattern with the callipers. Label this trace “4-Slit Pattern; w = 0.06 mm d = 0.13 mm”. Figure 36: 4-Slit; w = 0.06 mm; d = 0.13 mm Figure 37: 4-Slit; w = 0.06 mm; d = 0.13 mm Pattern 16) Move the graph paper up a couple of cm, and place the 40-slit diffraction grating (w = 0.06 mm and d = 0.06 mm) in the path of the laser beam making sure the slide is perpendicular to the beam, the beam passes through the centre of the grating, and the slits are vertical. Measure the radius from the slide to the screen. Trace this pattern on the graph paper and measure the distance (Δy) between adjacent dark fringes near the centre of the pattern with the callipers. Label this trace “40-Slit Grating Pattern; w = 0.06 mm d = 0.06 mm”. Figure 38: 40-Slit; w = 0.06 mm; d = 0.06 mm Figure 39: 40-Slit; w = 0.06 mm; d = 0.06 mm Pattern 17) Move the graph paper up a couple of cm, and place the 80-slit diffraction grating (w = 0.02 mm and d = 0.06 mm) in the path of the laser beam making sure the slide is perpendicular to the beam, the beam passes through the centre of the grating, and the slits are vertical. Measure the radius from the slide to the graph paper. Trace this pattern on the graph paper and measure the distance (Δy) between adjacent dark fringes near the centre of the pattern with the callipers. Label this trace “80-Slit Grating Pattern; w = 0.02 mm d = 0.06 mm”. Figure 40: 80-Slit; w = 0.02 mm; d = 0.06 mm Figure 41a: 80-Slit; w = 0.02 mm; d = 0.06 mm Pattern Figure 41b: 80-Slit; w = 0.02 mm; d = 0.06 mm Pattern Creative Commons Attribution 3.0 Unported License 16 PHYSICS COURSE NAME LAB x 18) Examine the 40 & 80-slit patterns. How does maxima spacing and sharpness change as the number of slits increase? Part 3. The Diffraction Grating: 19) Make sure the laser is still perpendicular to the wall by holding the mirror flat against the wall and make sure the reflected beam still reflects back into the laser aperture. If it does not then repeat steps 3 and 4 now. Our diffraction equation assumes the laser beam is set normal to the wall, so it is critical that the beam is perpendicular to the wall. 20) Tape a new piece of graph paper in ‘landscape’ orientation1 to the wall so that the laser beam strikes it in the centre near the top. (1The long dimension of the graph paper is horizontal. ) 21) Place the provided diffraction-grating (probably 500 lines/mm. but check it) in the path of the laser beam making sure the grating is perpendicular to the beam, the slits are vertical, and the laser beam passes through the approximate centre of the grating. (Be very careful not to get fingerprints on the grating.) Move the diffraction grating closer to the wall being careful to keep the beam passing through the approximate centre of the grating until you see 5 dots, one at centre, the 1st order pair on either side, and the 2nd order pair further out. If you can see all 5 dots, but they are too close together you can move the diffraction grating back toward the laser until the 5 dots have the maximum separation that you can use on your graph paper. Compare this pattern to the patterns obtained in Parts 1 and 2. 22) Measure the radius (distance r) from the diffraction grating to the graph paper. Trace the pattern on the graph paper and use the Vernier callipers or a ruler to measure the distance (Δy) between the 0th order spot to the 1st order maxima spot and record this on the graph paper for later. Measure the distance from the 0th order to the 2nd order as well and record this on the graph paper. Label this trace “500 lines/mm diffraction-grating Pattern”. Figure 42: 500 lines/mm Diffraction Grating Figure 43: 500 lines/mm Diffraction Grating Pattern 23) Usually in this lab exercise you are given the exact wavelength of the laser light and asked to calculate the actual number of lines/mm of the grating since this can vary due to temperature variations and other environmental conditions. Since the laser each student may have will vary, Creative Commons Attribution 3.0 Unported License 17 PHYSICS COURSE NAME LAB x we do not have this information for you. So, in this last step, assume the diffraction grating is actually the stated value (probably 500 lines/mm) and calculate the wavelength of the light your laser is emitting. Since the number of lines/mm can vary ±2% of the stated value, give an uncertainty for your final answer based on this uncertainty and the uncertainty of your measurements. Compare this to the wavelength of light your laser is rated at. (This should be written on the laser somewhere. The one used to prepare this lab was rated at between 630 nm and 680 nm.) Creative Commons Attribution 3.0 Unported License 18 PHYSICS COURSE NAME LAB x ANALYSIS AND/OR QUESTIONS Experiment L1 Laboratory Results Part 1: Half Barrier and Single Slits Sketch and label the pattern you saw with the half barrier; then sketch the pattern for the 1.50, 0.75, 0.50, 0.25, and 0.13 mm single slits: Pattern for Pattern Sketches Half Barrier 1-slit w 1.50mm 1-slit w 0.75mm 1-slit w 0.50mm 1-slit w 0.25mm 1-slit w 0.13mm Part 2: Multiple Slits nominal distance between slits Pattern Sketch Measured Fringe Separation ( y ) Radius from Slit to Screen (r) Calculated Wavelength ( ) 1-slit w 0.10mm 2-slit w 0.10mm d 0.20mm 2-slit w 0.10mm d 0.40mm 2-slit w 0.10mm d 0.70mm 3-slit w 0.06mm d 0.13mm 4-slit w 0.06mm d 0.13mm 40-slit w 0.06mm d 0.06mm 80-slit w 0.02mm d 0.06mm Creative Commons Attribution 3.0 Unported License 19 PHYSICS COURSE NAME LAB x Part 3: Diffraction Grating # lines/mm = _______________________ Calculated from lines/mm Fringe Separation (d) (Δy) Radius from the Cornell Slit-film to the Graph Paper (r) Calculated Wavelength (λ) 1st order right 1st order left 2nd order right 2nd order left Best estimate for wavelength (λ): _____ ± ____ Creative Commons Attribution 3.0 Unported License nm; 20 PHYSICS COURSE NAME LAB x REFERENCES From Original Lab Exercise: 1. Tipler, Paul: Physics for Scientists & Engineers, 3rd Ed. Worth Publishers, 1991. ISBN 0-87901432-6. P951, 981, 1068, 1075. 2. Ohanian, Physics, p806, Chp 38 p861, Chp 39.4-5 p871, Chp 40.1 3. Mayfield Publishing Co., Directions for Using Cornell Slitfilm Demonstrator, 1987. 4. Pedrotti, Introduction to Optics 2nd Ed. Prentice-Hall 1993. ISBN 0-13-501545-6. Original Lab Manual by Rick Nowel, E. Tech, COTR Adapted for Remote Delivery by Ron Evans, MSc Under the Remote Science Labs for Second Year Physics Project funded by BCcampus 2012 - 2013 Public domain images in Figures: 02, 03, 04, 05, 06, 07, and A1 were imported from the original lab manual that was produced by COTR. All other images were produced by Ron Evans and are covered by the CC license of this document. Creative Commons Attribution 3.0 Unported License 21 PHYSICS COURSE NAME LAB x Appendix 1: The Cornell Slit-film This is a map of the Cornell Slit-film. Use it to identify which slit pattern you are being asked to use. Figure A1: This is a map of the Cornell Slit-Film that is included in your lab kit. (Circled numbers indicate number of slits). Creative Commons Attribution 3.0 Unported License 22