Reflection and Mirrors Legacy Problem #2 Guided Solution
Problem*
A light ray approaches a mirror at an angle of 22° with the mirror surface. What is the angle of reflection of this light ray?
Audio Guided Solution
Perhaps one of the most fundamental laws governing the reflection of light off a surface is known as the Law of Reflection. The Law of Reflection states that the angle at which light approaches the surface is equal to the angle at which it reflects off the surface. These angles are generally known as the angle of incidence and the angle of reflection, and they are measured between the ray of light that approaches or reflects off the surface and a normal line drawn to the surface at the point of incidence. Thus, if the angle between the ray of light and the mirror surface is 22 degrees, then the angle of incidence is 90 degrees minus the 22 degrees, because we measure these angles of incidence between the perpendicular line, or normal line, and the ray of light. So by subtracting the angle between the ray of light and the surface from the 90 degrees, we get 68 degrees as the angle of incidence, and if that's the angle of incidence, then the angle of reflection is also 68 degrees.
Solution
68°
Habbits of an Effective Problem Solver
- Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
- Identify the known and unknown quantities in an organized manner. Equate given values to the symbols used to represent the corresponding quantity - e.g., \(\descriptive{d_o}{d_o,distance object} = 24.2\unit{cm}\); \(\descriptive{d_i}{d_i,distance image} = 16.8\unit{cm}\); \(\descriptive{f}{f,focal length} = \colorbox{gray}{Unknown}\).
- Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
- Identify the appropriate formula(s) to use. Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.
Read About It!
Get more information on the topic of Reflection and Mirrors at The Physics Classroom Tutorial.