Nuclear physics and semiconductors

Written by Dr. Hamza Farooq (Physics)

ECAT · Physics · 5 questions

Name: ____________________ Date: ____________

The binding energy per nucleon is greatest for nuclei with mass number around:
- A 56
- B 4
- C 120
- D 238
In an n-type semiconductor, the majority charge carriers are:
- A Protons
- B Holes
- C Positrons
- D Electrons
When a p-n junction diode is forward biased, the depletion region:
- A Disappears for good
- B Stays unchanged
- C Widens
- D Narrows
An alpha particle consists of:
- A Two electrons
- B Two protons and two neutrons
- C One proton and one neutron
- D A single neutron
Nuclear fission is the process in which:
- A A nucleus absorbs a photon only
- B An electron leaves the atom
- C A heavy nucleus splits into two lighter nuclei, releasing energy
- D Two light nuclei join to form a heavier nucleus

Answer key

1. A, 2. D, 3. D, 4. B, 5. C

Iron-56 and nearby nuclei are the most tightly bound, so fission of heavy nuclei and fusion of light ones release energy.
Doping with a donor such as phosphorus adds free electrons, which become the majority carriers.
Forward bias pushes carriers toward the junction, so the depletion region becomes narrow and current flows.
An alpha particle is the nucleus of a helium-4 atom: two protons and two neutrons.
In fission, a heavy nucleus such as uranium-235 splits after absorbing a neutron and releases a large amount of energy.