Photons do not travel in straight lines. Quantum particles do not have trajectories as classical particles do. Photons do not propagate in all directions as a spherical wave does.

One of light’s characteristic properties is that, in a transparent medium like air, glass, or still water, it travels in a straight line. Light exhibits characteristics of both waves and particles, the latter of which are described as packets of energy called photons.

Light waves travel in straight lines. Light waves travel faster than sound waves.

Like electromagnetic waves, mechanical waves, and (in fact) everything travels in a straight line until something acts on it causing it to stop going straight or until the medium it’s travelling in changes. Light will bend due to gravity, refraction, reflection.

Answer: When an opaque object is placed in the path of light, it blocks the light from passing through it. As light travels in a straight line and cannot bend itself around the object, it is not able to light up the space behind the object. This leads to the formation of a shadow.

In contrast, light waves can travel through a vacuum, and do not require a medium. There is one more aspect of wave travel to consider, which applies to both sound and light waves. As a wave travels from a source, it propagates outward in all directions.

Water affects light rays in a similar way. Some light will be reflected off the surface of the water, but much of the light will pass through the transparent water. When a light ray passes from air into water a similar thing occurs: the light ray is bent as it strikes the surface of the water.

Light waves change speed when they pass across the boundary between two substances with a different density , such as air and glass. This causes them to change direction, an effect called refraction . the light speeds up going into a less dense substance, and the ray bends away from the normal.

Once light has hit another surface or particles, it is then absorbed, reflected (bounces off), scattered (bounces off in all directions), refracted (direction and speed changes) or transmitted (passes straight through).