91Ó°ÊÓ

Light is incident on a plane mirror at an angle of \(40^{\circ}\) relative to the normal. What is the angle of reflection?

Light is incident on a plane mirror at an angle of \(30^{\circ}\) relative to its surface. What is the angle of reflection?

Show that for a person to see his or her complete (head-to-toe) image in a plane mirror, the mirror must have a length (height) of at least one-half a person's height (see Fig. 7.4 ). Does the person's distance from the mirror make a difference? Explain.

How much longer must the minimum length of a plane mirror be for a 6 -ft 4 -in. man to see his complete head-to-toe image than for a 5 -ft 2 -in. woman to do so?

If a material has an index of refraction of \(1.45,\) what is the speed of light in the material?

The speed of light in a particular type of glass is \(1.40 \times 10^{8} \mathrm{m} / \mathrm{s}\). What is the index of refraction of the glass?

What percentage of the speed of light in vacuum is the speed of light in water?

The speed of light in a certain transparent material is \(41.3 \%\) of the speed of light in vacuum. What is the index of refraction of the material? (Can you identify the material?)

Sketch a ray diagram for a concave mirror with an object at \(D_{\circ}=R\) and describe the image characteristics.

Sketch ray diagrams for a concave mirror showing objects at (a) \(D_{o} > R,\) (b) \(D_{o} > f\), and (c) \(D_{o} < f\). Describe how the image changes as the object is moved toward the mirror.