Video Transcript
The following figure shows light
rays being focused correctly by an eye. The object that the light comes
from is not shown. Are the light rays from a point on
a nearby object or from a point on a distant object? (A) The light rays are from a point
on a distant object. (B) There is no way to tell. (C) The light rays are from a point
on a nearby object.
This question is asking about
diverging light rays entering the eye from a point on an object some distance
away. It is asking us to determine if
this object is nearby, distant, or if there is no way to tell.
We know that two rays of light
traveling in the same direction are diverging if they move farther apart. Light rays that are converging move
closer together as they travel, while light rays that are parallel neither converge
nor diverge as they travel in the same direction. The two light rays entering the
observer’s eye are diverging. We can construct a ray diagram
showing light rays from a point on a distant object. Light from a point on a distant
object will diverge. An object that is very distant will
emit diverging light rays from a point.
If we zoom in on the eye in this
example, we can see that over very long distances, these light rays appear parallel
to each other. Light rays that are parallel must
be from a point on a distant object. Since the two light rays entering
our observer’s eye are diverging, option (A) cannot be the correct answer. We can construct a ray diagram
showing light rays from a point on a nearby object. Light from a point on a nearby
object will diverge. Since the two light rays entering
our observer’s eye are also diverging, option (C) must be the correct answer.
