# Diffraction pattern of a light beam from a narrow slit

1. Jul 12, 2010

Actually, I'm studying for my entrance exams to college.
I think the professor made a mistake.
So , the question says :

A diffraction pattern of a light beam from a narrow slit and from a thread are :
a)Completely identical
b)Totally different
c)Identical except for the center.

He choosed b , but I say a .

Who's correct and why , thanks a lot.

2. Jul 12, 2010

### collinsmark

Re: Diffraction.

I have to side with your instructor. The problem statement said "narrow slit" not double slit.

Assuming that both the "narrow slit" and the "thread" experiments involve a culminated laser beam as the light source, will either of them form an "interference" pattern in addition to any diffraction pattern? And when considering the diffraction pattern alone of the thread experiment (ignoring any possible interference pattern, just for the moment), does the width of the laser beam itself play a part in the resultant pattern?