A beam of electrons of speed v is incident on a double slit and then strikes a screen where it is made visible. If the speed of electrons is increased, the spacing between the bring regions on the screen.

Question

anonymous · Answer

I know that is answer is decrease I just can't remember the equation to prove it.

anonymous · Answer

Well.. in this case you look at the electrons as a wave right? 
so the electrons have a wavelength.

The equation for the wavelength is given by de broglie equation, so you can figure out what happens to the wavelength. 

Then using your knowledge of interference, you can figure out what happens to the spacing of the pattern as the wavelength changes ;-)!