מודלים של חומר מוצק, גרעין וחלקיקים
הוצג| English | משמעות |
|---|---|
| band gap/bænd ɡæp/ | מרווח אנרגטי |
| half-life/hɑːf laɪf/ | מחצית חיים |
A decision before an answer
- A semiconductor’s conductivity depends on available states and carriers, not merely on the number of electrons in the material.
- Your goal: Use band and carrier descriptions.
Read the relationship
- Filled bands cannot carry ordinary current without accessible nearby states. Metals have partially filled or overlapping bands; semiconductors have a small band gap. Donor and acceptor doping change carrier populations.
- Apply radioactive decay and binding-energy ideas.
After two half-lives, the remaining fraction is:
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Two successive halvings give one quarter.
Use the defining rule
- Fermi–Dirac occupancy is 1/[exp((E−μ)/(kT))+1]. At zero temperature it becomes a step at the Fermi energy; thermal broadening does not make every state half occupied.
- Check conservation laws in particle reactions.
Donor doping commonly supplies:
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Donor levels facilitate electron excitation into conducting states.
Check the conditions
- Radioactive populations obey N=N0e^(−λt), activity λN and half-life ln2/λ. Binding energy comes from a mass deficit multiplied by c²; compare binding energy per nucleon when discussing stability.
- Check conservation laws in particle reactions.
After three half-lives, N/N0=(1/2)^3=1/8, so activity is also one eighth if λ is unchanged. A mass defect of 0.010 u corresponds to about 9.315 MeV using 1 u c²=931.5 MeV.
After four half-lives, one part in ____ remains.
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2^4=16.
Apply the task format
- Nuclear and particle processes must conserve charge, energy, momentum and the applicable quantum numbers. Beta decay includes a neutrino or antineutrino; a two-body electron-only story cannot explain its continuous energy spectrum.
- Check conservation laws in particle reactions.
Activity and surviving population both decay, but their units differ: activity is transitions per second.
איזו תשובה מתאימה למקרה זה?
שימוש בתיאוריות פס ונושאי מטען
Charge conservation alone is sufficient to validate any particle reaction.
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Energy, momentum and other applicable conservation laws also matter.
Keep the distinctions
- band gap 带隙 — An energy interval with no allowed bulk electronic states in the band model.
- half-life 半衰期 — Time for a radioactive population to halve.
- Use band and carrier descriptions.
- Apply radioactive decay and binding-energy ideas.
- Check conservation laws in particle reactions.
Match each term with its precise meaning in this lesson.
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Keep the distinctions stated in the teaching example.
Put this lesson’s reasoning or event sequence in order.
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The order follows the stated process; check each stage before the next.