Caylee Villegas

2022-07-14

If photon is is emitted in random direction then how does a lens work?

Urijah Hahn

Expert

To think about light as a wave sometimes creates confusion.
The wave image is used to calculate intensity distributions of diffracted light behind edges and slits. This is almost the only calculation you can do for electromagnetic radiation, which is treated like waves. Another cases I see is the diffraction on thin films (oil on water) and for reflective surfaces.
If you think of light as a stream of photons, you might think of this: - A photon is an oscillating magnetic field and an oscillating electric field (moving at the speed of light) - Light is electromagnetic radiation from numerous photons. - A thermal source emits these photons in random moments, random directions, random energy content (frequency of its field oscillations). An oscillation of their common EM-fields, even for almost monochromatic light like from a sodium lamp, cannot be measured.
One generates an EM wave - instead of just EM radiation and with measurable oscillating electric and magnetic field components - from the excitation of a large number of electrons and accelerates them almost synchronously in an antenna rod (or any conductor; the electric line with alternating current always radiates). The emitted photons are radiated by the surface electrons and the shape of this surface determines whether the photons propagate in all (antenna rod) or some directions (e.g. horn antenna).
It is misleading to regard light only as a wave or only as a single photon that propagates in all directions and then collapses in one point.

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