Final answer:
If a light source is moved to the right, the shadow moves to the left. The direction of the light source's movement affects the shadow's position, illustrating the principle of light and shadow interaction. The Doppler effect explains how the frequency of light changes when the source of light moves relative to an observer.
Step-by-step explanation:
When a light source is moved to the right, the shadow of an object will move to the left, opposite to the direction of the light source's movement. This happens because as the light moves right, the angles at which the light rays are blocked by the object also shift, causing the shadow to appear on the side opposite to the light source's movement. If the light comes from the left of the subject, creating shadows on the right, the photo appears to have depth (looks 3D) due to the direction of light creating contrasting zones of light and shadow.
Furthermore, when the source of light is moving relative to an observer, the frequency of the waves changes; this is known as the Doppler effect. If the source of light moves toward the observer, it squeezes the waves together, increasing their frequency (which is perceived as blueshift), whereas if the source moves away from the observer, the waves are spread out, decreasing their frequency (perceived as redshift).
The way light rays change direction when crossing from one medium to another is based on changes in the speed of light in those media. When light slows down, it moves closer to the perpendicular, like a lawnmower moving from a footpath to grass. Conversely, when light speeds up, it moves away from the perpendicular, akin to a lawnmower moving from grass to a footpath.