Light

Photon

Definition

A photon is a particle of light defined as a discrete bundle (or quantum) of electromagnetic (or light) energy. Photons are always in motion and, in vacuum, travel at a constant speed to all observers.

Analogy

Think of photons like packets of energy delivered by the postman (light). Each packet contains specific information (energy), and they're constantly being sent out for delivery.

Related terms

Electromagnetic Spectrum: The range of all possible frequencies of electromagnetic radiation. It's like the menu from which the photon (the food item) comes from.

Quantum Mechanics: This is the branch of physics that deals with tiny particles like photons. It's like the rulebook for how our postman delivers his packets.

Energy Level: This refers to the quantized state of an atom where a photon can be absorbed or emitted. It's akin to different mailboxes where our postman can deliver his packets.