# Light and Optics

Hey guys i am stuck on two questions for the physics contest any idea how to do them?

A beam of wavelength 5.50 x 10^2 nm falls on a screen containing a pair of narrow slits seperated by 0.10 mm. Calculate the seperation between the two seventh order maxima on a screen 2.0 m from the slits.

and

Calculate the longest wavelength of light falling on double slits separated by 1.20 x 10^-6 m for which there is a first order maximum. In what part of the spectrum is this light?

any help would be appreciated. thanx

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I'll point you in the right direction. Read this, try it out and post back.

http://en.wikipedia.org/wiki/Diffraction

Look at the section titled single slit diffraction: Specifically under single slit diffraction.

A similar argument can be used to show that if we imagine the slit to be divided into four, six eight parts, etc, minima are obtained at angles θn given by

dsinθ= mλ

where m is an integer greater than zero

edit: i fail at latex