Wave-particle duality is an important idea that changes how we think about light. It shows us that light acts both like a wave and like a particle. This idea came about from important experiments and theories in the early 1900s.

Key Ideas

1. Wave Behavior:

   • Light can act as a wave. This means it can create patterns through interference and diffraction.
   • For example, in Young's double-slit experiment, light shines through two narrow slits and creates a pattern of bright and dark spots. This pattern is typical of waves, where some waves add up (bright spots) and some cancel each other out (dark spots).

2. Particle Behavior:

   • Light also behaves like a particle. We can see this in the photoelectric effect, where tiny bits of light called photons knock electrons out of a material.
   • The energy of these photons can be calculated with a simple formula: (E = hf). Here, (h) is a special number called Planck's constant (which is a tiny value of (6.626 \times 10^{-34} , \text{J s})), and (f) represents the frequency, or how often the light waves go up and down.

What This Means

• The idea of wave-particle duality makes us think differently about basic concepts in physics. It challenges the old view where light was only considered as a wave (like how Maxwell described it) or just a particle (as Newton described).
• Understanding wave-particle duality is essential for grasping quantum mechanics. It helps us with technologies like lasers and semiconductors.

This idea isn’t just for light; it also applies to matter. For instance, experiments with electrons show that they can also act like waves, just like light does.