Announcements This is the last experiment Next week is makeup week and you may only make up one experiment If you have a reason to wish to make up more than one contact Scott Whitmire sew1 buffalo edu If you are missing 3 or more reports you will fail this class Lab report grades are finalized the last day of class You must verify your scores before then as no changes will be made after that date See UBLearns for details regarding the date time location of the final exam Experiment MP5 Physical Optics In this experiment you will accomplish the following tasks 1 Study diffraction of light from a single slit 2 Study diffraction of light from a double slit 3 Study diffraction of light from a circular aperture 4 Study diffraction of light from a grating V 1 Diffraction from a single slit The apparatus shown will produce a pattern of bright and dark areas on the screen The locations x of these bright and dark areas or fringes will depend on L of the laser and the nature of the diffracting element For the first part of this experiment you will use a single slit of width 0 04 mm V 1 The intensity or brightness of the light is shown as a function of depends on W and The minima in intensity dark areas occur when where n in any integer This fact and the small angle approximation sin means that for the minima can be re written as sin A plot of vs n will have a slope s given by V 1 Use the setup shown in the figure on previous slides Use a single slit with width 0 04 Use 200 Place a paper sheet on the screen and trace the diffraction pattern shown in the figure below Mark the positions on all of the minima you can see Measure and record the locations of these marks VI 1 of the report Tabulate the data from V 1 Plot vs n Use LINEST to determine the slope Determine and report the slit width Compare this with the manufacturers stated value for W Assume the uncertainty in the wavelength of the laser is small enough to be ignored and that the uncertainty in L 0 2 See the manual for details V 2 Diffraction from a double slit There are now 2 terms governing the intensity one from the effects of a single slit dashed line and a second resulting from the fact that there are now 2 slits solid line V 2 Remove the single slit and replace it with the double slit that has 0 08 and a slit separation 0 25 Place a paper sheet on the screen and trace the diffraction pattern shown in the figure below Find 3 or 4 minima on either side of the central spot and record these on the paper V 2 The locations of the minima are given by 2 Measure and record the location of the minima you marked on the paper A plot of vs m will have a slope s of 2 VI 2 of the report Tabulate the data from V 2 Plot vs m Use LINEST to determine the slope Determine and report the slit separation in mm Compare this with the manufacturers stated value for a Assume the uncertainty in the wavelength of the laser is small enough to be ignored and that the uncertainty in L 0 2 See the manual for details V 3 Diffraction from a circular aperture Place the 0 08 mm circular aperture on the component carrier and set 50 0 cm On the paper mark the location of the first dark ring Measure and record the diameter of the dark ring The size of this minimum is given by sin 1 22 VI 3 of the report By the small angle approximation sin tan The diameter of the dark ring 2 Determine and report the diameter of the aperture Assume the uncertainty in the wavelength of the laser is small enough to be ignored and that the uncertainty in L 0 2 See the manual for details V 4 Diffraction from a grating The diffraction grating is a series of slits etched into glass There are 600 of these slits per mm With the previous experiments we were recording the locations of minima For the diffraction grating we will record the locations of the maxima With 50 0 place the meter stick on top of the black screen and adjust its position and orientation so that the central maximum 0 and two more spots are visible The location of maximum n is given by sin V 4 The diffraction pattern is shown in the figure below Grating diffraction pattern cs n 1 n 2 The angles here are too large to use the small angle approximation so The wavelength can be calculated using 1 tan 1 1 and 2 tan 1 2 sin 1 1 first order sin 2 2 2 second order d is the spacing between the individual lines on the grating Record the location and the uncertainty in the location for cs 1 for 1 and 2 for 2 VI 4 of the report Use the values for the location of the central spot and the n 1 diffraction maximum to determine 1 Use the uncertainties in these values to determine the uncertainty in 1 Repeat this for the 2 diffraction maximum Determine and report the wavelength of the laser as indicated by the value for 1 Repeat this for 2 See the manual for details Although not required the uncertainty in wavelength can be calculated using the equation given in question VII 1