AP Physics 2: Algebra-Based Flashcards: Reflection
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
How is a light ray's direction related to its wavefront?
A light ray always points in the direction of the wave's travel and is perpendicular to the wave's wavefront.
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How is a light ray's direction related to its wavefront?
A light ray always points in the direction of the wave's travel and is perpendicular to the wave's wavefront.
What is the 'normal' in the context of light reflection?
The normal is an imaginary line drawn perpendicular to the reflecting surface at the point where the incident ray strikes.
If the angle between the incident ray and the reflected ray is 100°, what is the angle of incidence?
The angle of incidence is 50°. The normal bisects the angle between the incident and reflected rays, so $ heta_i + heta_r = 100°$, and since $ heta_i = heta_r$, each must be 50°.
What is specular reflection?
Specular reflection is the reflection of light from a smooth surface, which results in light being uniformly reflected in a single direction.
Define a light ray.
A light ray is a straight line that is perpendicular to a light wave's wavefront and points in the direction of the wave's travel.
A laser beam hits a flat mirror. The angle between the incident beam and the surface of the mirror is 20°. What is the angle of reflection?
The angle of reflection is 70°. The angle of incidence is measured from the normal, so $ heta_i = 90° - 20° = 70°$, and thus $ heta_r = 70°$.
What kind of surface causes specular reflection?
A smooth surface, such as a mirror or calm water, causes specular reflection.
What is the mathematical equation that summarizes the law of reflection?
The law of reflection is summarized by the equation $ heta_r = heta_i$, where $ heta_r$ is the angle of reflection and $ heta_i$ is the angle of incidence.
If an incident light ray strikes a mirror at an angle of 40 degrees to the normal, what is the angle of the reflected ray relative to the normal?
The angle of the reflected ray is 40 degrees. According to the law of reflection, the angle of incidence equals the angle of reflection ($ heta_r = heta_i$).
State the law of reflection.
The law of reflection states that the angle between the incident ray and the normal is equal to the angle between the reflected ray and the normal.