EM Waves & Atoms (Edexcel GCSE Physics: Combined Science)

• Atoms can interact with electromagnetic (EM) waves in one of two ways, they can be:
  • Absorbed
  • Emitted

• When an EM wave hits an atom, it can be absorbed by one of the electrons giving it energy
  • This causes the electron to move up to a higher energy level

• Then an electron will move back down to a lower energy level and will emit an EM wave in the process

The electrons orbiting atoms can absorb and emit EM waves by moving between different energy levels

• In this way, atoms can absorb and emit electromagnetic waves over a wide range of frequencies depending on the gap between the energy level that the electron has moved
• The energies associated with electron transitions tend to be in the visible and ultraviolet range (and sometimes X-rays)
• Higher energies (ie. gamma rays) can only be achieved when EM waves interact with the nucleus
  • The nucleus of an atom can absorb and emit EM waves in a similar way to electrons