Problems

Some telephoto cameras use a mirror rather than a lens. What radius of curvature is needed for a concave mirror to replace a 0.800 -m focal-length telephoto lens?

1. 0.400 m
2. 1.60 m
3. 4.00 m
4. 16.0 m

What is the focal length of a makeup mirror that produces a magnification of 2.00 when a person’s face is 8.00 cm away?

1. –16 cm
2. –5.3 cm
3. 5.3 cm
4. 16 cm

An optical fiber uses flint glass (n = 1.66) clad with crown glass (n = 1.52) . What is the critical angle?

1. 33.2°
2. 23.7°
3. 0.92 rad
4. 1.16 rad

Suppose this figure represents a ray of light going from air (n = 1.0003) through crown glass (n = 1.52) into water, similar to a beam of light going into a fish tank.

Calculate the amount the ray is displaced by the glass (Δx), given that the incident angle is 40.0° and the glass is 1.00 cm thick.

1. 0.839 cm
2. 0.619 cm
3. 0.466 cm
4. 0.373 cm

A camera’s zoom lens has an adjustable focal length ranging from 80.0 to 200 mm . What is its range of powers?

1. The lowest power is 0.05 D and the highest power is 0.125 D.
2. The lowest power is 0.08 D and the highest power is 0.20 D.
3. The lowest power is 5.00 D and the highest power is 12.5 D.
4. The lowest power is 80 D and the highest power is 200 D.

Suppose a telephoto lens with a focal length of 200 mm is being used to photograph mountains 10.0 km away. (a) Where is the image? (b) What is the height of the image of a 1,000-m-high cliff on one of the mountains?

1. (a) The image is 0.200 m on the same side of the lens. (b) The height of the image is – 2.00 cm.
2. (a) The image is 0.200 m on the opposite side of the lens. (b) The height of the image is – 2.00 cm.
3. (a) The image is 0.200 m on the opposite side of the lens. (b) The height of the image is +2.00 cm.
4. (a) The image is 0.100 m on the same side of the lens. (b) The height of the image is +2.00 cm.