1. Consider a beam of electrons with energy exactly 1 eV, flying exactly
in y-direction (i.e. no momentum in x-direction, px=0 and Dpx=0). You now
measure the x-position of the electrons by placing an aperture with 5 nm
width into the beam. What is the consequence? x y
(A) I now know the x-position of the electrons within 5 nm The electrons continue straight on along the y-direction, just like before the measurement.
(B) I now know the x-position of the electrons within 5 nm The electrons are deflected and acquire some momentum in x-direction, now flying faster than before.
(C) I now know the x-position of the electrons within 5 nm The electrons are deflected and acquire some momentum in x-direction, slowing down accordingly w.r. to their momentum along y-direction.

2. Consider a beam of electrons with energy exactly 1 eV, flying exactly
in y-direction (i.e. no momentum in x-direction, px=0 and Dpx=0). You now
measure the x-position of the electrons by placing an aperture with 5 nm
width into the beam. What is the consequence? x
(A) I now know the x-position of the electrons within 5 nm The electrons continue straight on along the y-direction, just like before the measurement.
(B) I now know the x-position of the electrons within 5 nm The electrons are deflected and acquire some momentum in x-direction, now flying faster than before.
(C) I now know the x-position of the electrons within 5 nm. The electrons are deflected and acquire some momentum in x-direction, slowing down accordingly w.r. to their momentum along y-direction. Before slit: Dpx = 0  we do not know the y-position of the electrons at all! Dx =  After slit: Dx = 5 nm  Dpx = ħ/10 nm .... we cannot circumvent HUP! y

3. Note: The slit results in diffraction of the matter wave, which
introduces the uncertainty in py as shown below. You already know
this behavior from diffraction of light at a slit! y x
screen

4. The conservation of total mechanical energy of a particle means that …
(A) … the sum of heat and kinetic energy is a constant.
(B) … the potential energy of the system is a constant.
(C) … the sum of kinetic and potential energy is a constant.
(D) … the particle has always the same velocity.

5. The conservation of total mechanical energy of a particle means that …
(A) … the sum of heat and kinetic energy is a constant.
(B) … the potential energy of the system is a constant.
(C) … the sum of kinetic and potential energy is a constant.
(D) … the particle has always the same velocity.