Electrons Flashcards
What is the Lorentz force?
The total force on a charged particle from electric and magnetic fields: F=qE+q(v×B).
How does a cathode ray tube work?
Electrons are accelerated between cathodes with different voltages. Direction is controlled by magnetic fields, and electrons are displayed on a fluorescent screen.
What is solar wind?
The Sun emits protons, electrons, and heavy ions. Earth’s magnetic field deflects these particles, protecting the planet.
What does quantisation mean in quantum theory?
Everything can be “quantised” into packets, such as light, energy, and charge.
How is an electron’s location described in quantum theory?
The wavefunction is a probability distribution indicating where an electron might be.
What is the ground state of an electron?
The lowest energy state of an electron, where it cannot have less energy. Energy transitions require quantised energy levels.
What are fermions?
A class of subatomic particles, including electrons. The Pauli exclusion principle states no two identical fermions can occupy the same quantum state.
What are quantum numbers?
Numbers characterising the wavefunction of an electron:
Principal quantum number: Energy level.
Angular momentum quantum number: Orbital shape.
Magnetic quantum number: Orbital orientation.
Spin quantum number: Spin up or down.
What are Fermi-Dirac statistics?
Describes the probability of finding an electron in any state. At T=0, all states below the Fermi energy are full, while those above are empty.
What is Fermi energy?
The energy level where there is a 50% probability of occupation.
