1. What is the radius of a H atom?
(A) 52.9 pm
(B) 52.9 nm
(C) 5.29 fm
(D) 529 Å
(E) None of the above.

2. What is the radius of a H atom?
(A) 52.9 pm
(B) 52.9 nm
(C) 5.29 fm
(D) 529 Å
(E) None of the above.

3. Photons have momentum as seen earlier. Einstein’s equation E = mc2
obviously plays an important role here. Also, for photons:
E = mc2 = h
Which of the following statements is true for matter (as opposed to light)?
(A) Ekin = p2/2m
(B) Ekin = mc2
(C) Both (A) and (B)

4. Photons have momentum as seen earlier. Einstein’s equation E = mc2
obviously plays an important role here. Also, for photons:
E = mc2 = h
Which of the following statements is true for matter (as opposed to light)?
(A) Ekin = p2/2m
(B) Ekin = mc2
(C) Both (A) and (B)
IMPORTANT NOTE:
For light (photons): E = mc2 = h ; p = mc = E/c = h/c = h/;  = h/p
For matter:
Ekin = p2/2m; p = mv;  = h/p; but: Ekin is not mc2 !
E = mc2 is not the kinetic energy, but the total relativistic energy!
The big difference is that light has no invariant mass or rest mass,
while matter does! The result is that E = mc2 is HUGE for matter!
One electron has 511 keV mass energy! A light field of 532 nm with the
same total energy needs ca. 219,000 green photons!

5. The Double Slit Experiment
(A) Each electron went through either the left slit or the right slit. If we had a
good enough detector, we could determine which one without changing the
interference pattern.
(B) Each electron went through either the left slit or the right slit, but it is
fundamentally impossible to determine which one.
(C) Each electron went through both slits. If we had a good enough detector,
we could measure an electron in both places at once.
(D) Each electron went through both slits. If we had a good enough detector,
we could measure an electron going through one slit or the other, but this
would destroy the interference pattern.
(E) It is impossible to determine whether the electron went through one slit
or both.

6. The Double Slit Experiment
(A) Each electron went through either the left slit or the right slit. If we had a
good enough detector, we could determine which one without changing the
interference pattern. Shown by experiment to be incorrect.
(B) Each electron went through either the left slit or the right slit, but it is
fundamentally impossible to determine which one Shown by experiment to be incorrect Also: Would not create interference pattern!
(C) Each electron went through both slits. If we had a good enough detector,
we could measure an electron in both places at once.
Disagrees with experiment (not shown in class)
(D) Each electron went through both slits. If we had a good enough detector,
we could measure an electron going through one slit or the other, but this
would destroy the interference pattern.
(E) It is impossible to determine whether the electron went through one slit
or both. Disagrees with experiment (not shown in class)