Light as a wavelength I am learning that light is an electromagnetic wave, does this wave travel in every direction simultaneously from the source of light? I am trying to visualize this concept but I haven’t seen an explicit definition saying there are infinitely many wavelengths emitted from a source of light. Would like some clarification on this, thanks.
 A: What direction the light travels from the source, and what range of wavelengths the light contains are separate questions.
The sun emits light in all directions, and (in principle) in all wavelengths according to its (very nearly ideal) blackbody spectrum.
A laser (typically) emits light in a narrow beam, with a very narrow range of wavelengths. But you could use a laser to illuminate a scattering object of some kind, and produce light travelling in nearly all directions but still with a narrow range of wavelengths.
An LED (light-emitting diode) emits light in all directions, although typically some angles are blocked by the structure supporting the LED, and often a lens is incorporated in the LED package to reduce its output to a broad beam with perhaps 60 degree half-angle. The wavelengths emitted by an LED are much broader than from a laser, but typically only span a few 10's of nanometers (For example, from 650-680 nm).
Fluorescent materials similar to LEDs have narrow, but not laser-like, spectra, and emit in all directions.
And so on.
A: Let's take the case of an old-school light bulb containing a hot filament as an example. When hot enough to emit light (as in a car headlight) it produces a broad mix of wavelengths that is not infinite in its range but does cover pretty much the entire visible spectrum- thereby producing what we perceive as white light or something close to it.
In this operating regime, the hot filament is producing a truly gigantic number of photons of different wavelengths every second in all possible directions- so many in fact that we do not bother trying to count the individual photons, but instead describe the light emitted into spherical space as electromagnetic radiation (light waves) whose intensity falls off as (1/radius squared).
A: The first thing I'd recommend is to get in the mindset of how waves move.  Find a still pool of water, and toss a small rock into the middle of it.  Observe the waves moving outwards in all directions.  Do we call this "infinitely many waves?"  Or is there just one wave reaching outward?
One thing that can be confusing is that we also say that light is made of photons.  A photon is a particle that has one clear direction.  Sometimes you can treat a light wave like a very large number of photons.  Photons are very small, so one can emit quite a lot of them.  A mere 60W light bulb emits 180,000,000,000,000,000,000 photons every second!  So you can think of the light wave as the sum of those 180 pentillion photons per second.  This view would be similar to thinking of the myriad water molecules bobbing up and down in the ripples of the pond.
A: We obviously have three phenomena that you should take into account in your consideration of light as a wave. The first concerns the generation of light. The second concerns the intensity distribution behind edges and the third concerns the generation of radio waves.
Light generation
This occurs when subatomic particles, first and foremost electrons, are energetically excited. When they fall back to their initial level in the atom, they emit electromagnetic radiation. Or it happens when ions in gases change their direction when they collide. It also happens when surface electrons in a conductor are periodically moved.
Light diffraction
In slit experiments, it can be observed that an intensity distribution of radiation occurs on an observation surface. That this intensity distribution must consist of individual photons follows from 1.
In fact, there are the experiments in which individual photons are gradually deflected onto the screen. The intensity distribution (fringe pattern) is thereby statistically visible after a longer observation time.
Although this phenomenon can be described by interference formulae, interference with the extinction of photons does not take place at all. Instead, the photons are deflected at the edges in such a way that the swelling intensity distribution occurs.
Radio waves
The first radio waves had wavelengths that made it possible to study their properties in the experimental hall. Hertz measured such radiation and found that it had a magnetic field component and an electric component. Both were directed 90° to each other and both 90° to the direction of propagation.
From phenomenon 1 it follows again that this radiation must consist of photons, because there is no other light generation than from the emission of energetically excited particles. And indeed, a radio wave is generated by accelerating surface electrons back and forth in the antenna rod and thereby emitting polarised photons. The intensity of the emissions themselves is periodic, because the electrons on the antenna rod are also periodically accelerated.
The radio radiation of a stationary rod actually radiates horizontally in all directions equally. However, directional antennas can also be built.
Light as a wave
I haven’t seen an explicit definition saying there are infinitely many wavelengths emitted from a source of light.  An incandescent lamp, like any other body above 0 Kelvin, emits EM radiation in a broad spectrum. There are countless photons that are emitted from the most diverse excitation states. These photons are neither polarized - their electric or magnetic field components are not aligned - nor can periodic intensity fluctuations be determined.
In order to obtain a wave character of the radiation, the synchronized periodic excitation of the emitting particles is required.
