# Question Video: Determining the Path of Reflected Light Rays Science

The following figure shows two light rays from the same point that are both incident on different parts of a concave mirror. When these light rays are reflected, will the paths of the reflected light rays cross each other?

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### Video Transcript

The following figure shows two light rays from the same point that are both incident on different parts of a concave mirror. When these light rays are reflected, will the paths of the reflected light rays cross each other? (A) Yes, they will cross each other. (B) No, they will not cross each other. Or (C) there is no way to tell.

In this question, we’re shown two light rays, A and B. These light rays are both incident on a concave mirror. Let’s begin by labeling the optical axis and the focal point of the mirror. With the optical axis labeled, we notice immediately that incident ray A is parallel to the optical axis. This means that the reflected ray of incident ray A will pass through the focal point of the mirror.

For incident ray B, this isn’t the case. So, we will have to use the law of reflection to determine where its reflected ray goes. The law of reflection tells us that the angle of reflection of a ray of light is equal to its angle of incidence. And we should remember that these angles are measured from the normal of the surface that the light ray is reflecting off. Drawing the normal of the concave mirror at the point that incident ray B reflects and its angle of incidence, we can now draw the reflection of ray B.

Now that we’ve drawn both reflected rays on the diagram, we can see that they cross at this point here. Therefore, answer option (A) is the correct answer. When the two light rays are reflected, yes, they will cross each other.