 µ IB | Waves + Particles

10 quick questions

10 minutes maximum! (can you do it in 5?)

Constructive and destructive interference patterns can be produced with..

• A. only photons.
• B. only photons and electrons.
• C. only electrons and protons.
• D. photons, electrons and protons.

2. The formula E= hf can be used with..

• A. only photons.
• B. only photons and electrons.
• C. only electrons and protons.
• D. photons, electrons and protons.

3.The energy levels of electrons in a hydrogen atom can be calculated using the Bohr model.

Which of the following formulas can be used to calculate the energy released (as a photon) when an electron drops from n=2 to n=1? 4. For an electron orbiting the hydrogen nucleus, what is the quantity mvr equal to ?

• A. The centripetal force required to maintain a circular orbit.
• B. The angular momentum of the electron.
• C. The energy of the electron.
• D. The linear momentum of the electron at any point.

5.A high energy photon can instantaneously produce matter from energy through the process of pair production. An example of this is:

• A. A photon producing a neutron and a proton.
• B. A photon producing two neutrons.
• C. A photon producing a proton and an electron.
• D. A photon producing an electron and a positron.

6. For an electron to be trapped in the nucleus of an atom, its position must be known to an accuracy of about 10-15 m. This means the uncertainty in the momentum must be of the order of

• A. 10-15 kg ms-1
• B. 10-17 kg ms-1
• C. 10-19 kg ms-1
• D. 10-21 kg ms-1

7-10. An electron has kinetic energy Ee. It is trapped by two potential barriers of energy Eb as shown in this diagram.
Eb > Ee, so using classical physics, the electron cannot escape. However the electron still has a small chance of appearing on the other side of these barriers. 7. What is the name of this effect?

• A. Quantum tunnelling.
• B. Barrier jumping.
• C. Wave function tunnelling.
• D. Probability tunnelling.

8. How do the following changes affect the probability of the electron appearing on the other side of the barrier?

 Increase the width W Increase the quantity (Eb-Ee) A no effect no effect B lower probability no effect C no effect lower probability D lower probability lower probability

9. Which of these is proportional to the probability of finding the electron at a particular location?

• A. The wave function
• B. The square of the wave function
• C. The angular momentum
• D. The square of the angular momentum

10. Which of these statements about the value of the wave function is correct?

 Within the barrier Outside the barrier A zero at all points zero at all points B non-zero zero at all points C zero at all points non-zero D non-zero non-zero