A cosmetics manufacturer must decide whether to supply customers with a plane mirror…
PHYSICS · Subjective · CBSE · Physics · Light — Reflection and Refraction · Light — Reflection and Refraction
Problem
A cosmetics manufacturer must decide whether to supply customers with a plane mirror or a concave spherical mirror as the primary surface of a new handheld makeup device. The device will normally be held between 10 cm and 25 cm from the user’s face.
(a) Describe the characteristics (real or virtual, upright or inverted, magnified or reduced) of the images produced by a concave spherical mirror when the object is located (i) closer to the mirror than the focal point and (ii) farther from the mirror than the center of curvature.
(b) A prototype concave mirror has a focal length of 15 cm. Qualitatively determine the location, orientation, and relative size of the image of a person’s eye when the mirror is held 20 cm from the eye.
(c) Contrast the user experience when a plane mirror is substituted for the concave mirror at the same distance range. In your discussion, explain which mirror type better satisfies the goals of (i) precise eyelash application and (ii) a natural full-face view.
(d) Identify one practical drawback that might arise from using the concave design in a handheld device and explain the underlying optical reason.