Chapter 10.2, Problem 7P

'A concave mirror is a mirror that curves In, like a bowl, so that the normal lines on the reflective side of the mirror point toward each other. Makeup mirrors are often concave. The left side of Figure 10.55 shows an eye looking into a concave makeup mirror. The right side of Figure 10.55 shows an eye looking into an ordinary flat mirror. Trace the two diagrams in Flgure 10.55 and, in each case, show where a woman applying eye makeup sees her eye in the mirror. Use the laws of reflection to show approximately where the woman sees the top of her reflected eye and where she sees the bottom of her reflected eye. (Assume that the woman sees light that enters the center of her eye.) Notice that the figure shows the normal lines to the concave mirror. Based on your drawings, explain why a concave mirror makes a good mirror for applying makeup. (By the way, although a concave mirror is curved in the same direction as the bowl of a spoon, the smaller amount of curvature in a concave mirror prevents it from reflecting your image upside down, as a spoon does.)

 
Figure 10.55 an eye looking in a concav mirror and flat mirror.