alleryStart learning →In geometric optics, what does the word ray mean?
AA straight line that starts at some point
BA curved path that bends round obstacles
CA wavefront spreading in all directions
DA beam that widens steadily as it goes
Answer & Solution
Correct answer: A. A straight line that starts at some point
1. The word ray is borrowed from mathematics, where it means a straight line that originates at some point.
2. Light is modelled as travelling along such straight lines between the places where it meets matter.
3. A ray may change direction at a mirror or at a boundary, but between those events it stays straight.
4. Curved paths and spreading wavefronts belong to the wave description, not to the ray model.
_Source: OpenStax College Physics (CC BY 4.0), Ch 25 "Geometric Optics", section 25.1 The Ray Aspect of Light_
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