Question

In a double slit experiment with a single electron, a very thin film of fluorescent material that emits a photon whenever an electron passes through is placed on one of the slits to check which slit the electrons goes through. Describe the resulting pattern on the detecting screen if the experiment is repeated many time

Answer 1

The instant you observe the electron it is there, but the instant later, where is it?
No change in the detecting screen will be observed. It is as if electrons are passing through both slits.