Experiment 2

Experiment 2.14 INTERFERENCE OF LIGHT

AND

THE GRATING

ANALYSIS

1. Determine the central wavelength for red, green, and blue from the grating data. Record the wavelengths in cells F23:F25. The number of lines per centimeter for this grating is 5276 lines/cm. This value can be used to get d, the grating spacing, and the values of D and s will give you θ.

2. From the limit data, determine the wavelengths of the edges and record in cells F33:F36. Determine the range of wavelengths Δλ,which correspond to red light and to violet light, and enter in cells G39 and G41, respectively.

3. Answer Question 2 on the Worksheet.

4. The average of the right- and left-hand scale displacements of the Na yellow line should be already entered in cell D54. Use the relation between the scale displacement s, the grating-to-scale distance D to determine the sine of the projection angle θ and enter it in cell D56 :

HINT: Use the spreadsheet to find the sine of the projection angle q in cell D56 as follows:

"= D54/SQRT(D54^2 + D27^2)"

5. Use the grating equation with order number n = 1 to calculate the wavelength of the line:

MAX:

6. Enter the result in cell D58 and compare with the accepted value of 589.2 nm. Calculate the percent error in your measurement and enter the result in cell D60.

7. Print out the Worksheet and use it to develop your lab report.