# Homework Help: Physics problems: Help Edition

1. Apr 22, 2004

### mustang

Problem 6. A sodium-vapor street lamp produces light that is nearly monochromatic. If the light shines on a wooden door in which there are two straight, parallel cracks, an interfernece pattern will form on a distant wall behind the door. The slits have a separation of 0.3740mm, and the second-order maximum occurs at an angle of 0.18046 degrees from the central maximum.
determine the angle of the fourth-order minimum. Answer in degrees.
Would it be:
d sinθ = (m+1/2)λ
(0.3740*10^-3)sinθ = (m+1/2)λ does m=3?
Problem 15. By attaching a diffraction-grating spectroscope to an astronomical telescope, one can measure the spectral lines from a start and determine the start's chemical composition. Assume the grating has 3224 slits/cm. The wavelengths of the star's light are wavelength_1=463.200nm, wavelength_2=640.500 nm, and wavelength_3=704.700 nm.

Find the angle at which the second-order spectral line for wavelength 1 occurs. Answer in deg
rees.

2. Apr 23, 2004

### gnome

Problem 6:
What are you going to use for &lambda;?

Problem 15:
This is pretty much just plugging numbers into a equation. What's your question?