What is the difference between nuclear fission and nuclear fusion?

Fission is the splitting of a heavy nucleus (like Uranium) into smaller nuclei, releasing energy. Fusion is the combining of light nuclei (like Hydrogen isotopes) to form a heavier nucleus, which releases even more energy and powers the Sun.

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Core Study Guide

Modern Physics

Quantum mechanics, relativity, and atomic structures.

Modern physics describes physical phenomena at subatomic scales or extreme velocities. It is defined by quantum mechanics and relativity.

This unit covers the Photoelectric Effect, Einstein's mass-energy equivalence, Bohr's atomic model, and nuclear fission/fusion reactions.

Key Takeaways

•Light energy is quantized into photons; electrons are only ejected if photons exceed a work function threshold.
•Mass and energy are equivalent and interconvertible.
•Quantum mechanics describes particles in terms of probability wave functions.

Core Concepts & Definitions

1The Photoelectric Effect

The emission of electrons when light shines on a metal surface.

•Ejected electron kinetic energy: KE_max = h * f - Φ_work.

•Increasing light intensity increases electron count but not their kinetic energy.

2Mass-Energy Equivalence

Albert Einstein proved that mass and energy are different forms of the same physical quantity.

•E = m * c².

•Small mass defects in nuclear reactions release massive amounts of energy.

Quick Revision Notes

•Planck's constant h ≈ 6.626 × 10⁻³⁴ J·s.
•The threshold frequency is the minimum frequency of light required to eject electrons from a metal.