- #1
lovelylm1980
- 18
- 0
White light containing wavelengths from 405 nm to 760 nm falls on a grating with 7510 lines/ cm. How wide is the first-order spectrum on a screen 2.29 m away?
I'm not sure the way this question is worked out, but what I have so far is
sin(theta)=[m*Lambda+ m*Lambda]/d
d=1/7510cm=1.33e-6m
sin(theta)=[(407e-9m)+(705e-9m)]/1.33e-6m= 0.876 theta=61 degrees
width=2x(tan theta)=(2*2.29)*(tan 61)=8.32m
I have the wrong answer so I must have done something wrong. Can someone help?
I'm not sure the way this question is worked out, but what I have so far is
sin(theta)=[m*Lambda+ m*Lambda]/d
d=1/7510cm=1.33e-6m
sin(theta)=[(407e-9m)+(705e-9m)]/1.33e-6m= 0.876 theta=61 degrees
width=2x(tan theta)=(2*2.29)*(tan 61)=8.32m
I have the wrong answer so I must have done something wrong. Can someone help?