# Intro to quantum help

1. Dec 8, 2003

### philosophy42

hello all,
i'm a college freshman and have a physics problem that i am haing a tough time figuring. Here is the problem

"Neutrons travelling at 0.400m/s are directed through a double slit apparatus having 1.00-mm separation. An array of detectors is placed 10.0 m from the slits. A) How far off axis is the first zero intensity point on the detector array? B) WHen a neutron traches a given dectector, can we say which slit the neutron passed through? C) Write a wave function that describes a neutron in this expereiment."

I understand parts of the question, such that we cannot tell which slit the neutron passed through because of the heisenberg uncertainty principal. I am having trouble becuase I believe that i need to know the wavelength of the neutrons however am only given the speed and donnot know how to get the wavelength from the speed with out to frequency. To find the first dark spot on the detection panel i was going to use the equation, y(dark) = (m = 1/2)* ((wavelength * L(dist from slit to dectector))/(distance between slits d)) am i way off here and how am i suppose to figure out wavelength, or because I am dealing with the duality of the particle being botha wave and a particle am i not suppose to have a wavelenth and figure the problem another way. Any help would be wonderful, thank you.

2. Dec 8, 2003

### Ambitwistor

Look up "Compton wavelength".