Page 409 - Schaum's Outline of Theory and Problems of Applied Physics

394 SPHERICAL MIRRORS [CHAP. 31

31.3. A magnification that is negative means that the image is
(a) erect (c) smaller than the object
(b) inverted (d) larger than the object

31.4. An erect image is formed by a concave mirror when the object distance is
(a) less than f (c) between f and 2 f
(b) f (d) greater than 2 f
31.5. A concave mirror forms an enlarged image of an object
(a) for no values of p (c) when p is more than 2 f
(b) when p is less than 2 f (d) for all values of p

31.6. A convex mirror forms an enlarged image of an object
(a) for no values of p (c) when p is more than 2 f
(b) when p is less than 2 f (d) for all values of p

31.7. The focal length of a convex mirror whose radius of curvature is 24 cm is
(a) −12 cm (c) +12 cm
(b) −48 cm (d) +48 cm

31.8. A candle 6 cm high is 40 cm in front of a concave mirror whose focal length is +60 cm. The image is
(a) 2 cm high, erect (c) 2 cm high, inverted
(b) 18 cm high, erect (d) 18 cm high, inverted
31.9. The candle of Question 31.8 is 100 cm in front of the same mirror. The image is now

(a) 4 cm long, erect (c) 4 cm long, inverted
(b) 9 cm long, erect (d) 9 cm long, inverted

31.10. A candle 6 cm high is 40 cm in front of a convex mirror whose focal length is −60 cm. The image is
(a) 3.6 cm long, erect (c) 3.6 cm long, inverted
(b) 10 cm long, erect (d) 10 cm long, inverted

Supplementary Problems

31.1. What does a positive magnification signify? A magnification that is less than 1?
31.2. Under what circumstances does a concave mirror produce a real image of a real object? A virtual image?

31.3. A moth flies toward a convex mirror. Does its image become larger or smaller as it approaches the mirror’s focal
point? What kind of image is it?

31.4. (a) A concave mirror has a radius of curvature of 30 cm. What is its focal length? (b) A convex mirror has a radius
of curvature of 30 cm. What is its focal length?
31.5. A match 6 cm long is placed 30 cm in front of a concave mirror whose focal length is 50 cm. Find the location, size,
and nature of the image.

31.6. The match of Prob. 31.5 is placed 50 cm in front of the same mirror. Find the location, size, and nature of the image.
31.7. The match of Prob. 31.5 is placed 80 cm in front of the same mirror. Find the location, size, and nature of the image.