Question

Diffraction Grating	Column1	Column2	Column3	Column4	Column5	Column6	Column7	Column8
Data						Calculations
λ (nm)	lines/mm	L (cm)	Mode             (m or p)	y (cm)		Calc. Angle	Obs. Angle	%D
532	600	600.1	1	104.5
532	600	373.0	1	127.2
532	600	600.1	2	126.4
532	600	373.0	2	289.3
650	600	221.0	1	100.0
650	600	357.9	1	151.1
650	600	221.0	2	417.0
650	600	357.9	2	448.1

• Using the part 1 data from your physics lab above calculate the following; calculated angle, observed angle and percent difference (show all work outside the table)
• For parts 1, 2, 3, and 4., use L and y to calculate the observed angle. Excel works in radian mode. You can force it into degree mode by using: sin(radians(B4)) or degrees(asin(C4/D4)) where B4 is your angle in degrees and C4 and D4 would be distance measurements.
• For parts 1, 2, and 3, use the wavelength, order number, etc., to calculate the expected angle.
• For parts 1, 2, and 3, calculate the percent difference between the observed and expected angle.

Answer 1

For a grating, the observed angle is given by

The theoretical value of angle is given by the grating equation,

Where d is the separation between the lines of the grating.

Here, the grating has 600 lines per mm. So, separation between lines,

d = 1mm/600 = 1.667*10^-6 m

Thus,

The percentage difference is

Thus the tabular column can be filled as

The values marked as red is showing too much error from the theoretical value.