The unit vector along an incident ray is (3î - 4ĵ)/5. The reflecting surface is parallel to the x-axis. What is the unit vector along the reflected ray?
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Question

The unit vector along an incident ray is (3î − 4ĵ)/5. The reflecting surface is parallel to the x-axis. What is the unit vector along the reflected ray?

G1 Physics · Accepted Answer

The tangential x-component is unchanged and the normal y-component reverses. Therefore êᵣ=(3î+4ĵ)/5.