### Multiple Choice

In geometric optics, a straight line emerging from a point is called a (an) ________.

- ray
- focal point
- image
- object distance

An image of a 2.0 -cm object reflected from a mirror is 5.0 cm tall. What is the magnification of the mirror?

- 0.4
- 2.5
- 3
- 10

Can a virtual image be projected onto a screen with additional lenses or mirrors? Explain your answer.

- Yes, the rays actually meet behind the lens or mirror.
- No, the image is formed by rays that converge to a point in front of the mirror or lens.
- Yes, any image that can be seen can be manipulated so that it can be projected onto a screen.
- No, the image can only be perceived as being behind the lens or mirror.

What does *c* represent in the equation
$n=\frac{c}{v}$ ?

- the critical angle
- the refractive index
- the speed of light in a vacuum
- the speed of light in a transparent material

What is the term for the minimum angle at which a light ray is reflected back into a material and cannot pass into the surrounding medium?

- critical angle
- incident angle
- angle of refraction
- angle of reflection

Consider these indices of refraction: glass: 1.52, air: 1.0003, water: 1.333. Put these materials in order from the one in which the speed of light is fastest to the one in which it is slowest.

- The speed of light in water > the speed of light in air > the speed of light in glass.
- The speed of light in glass > the speed of light in water > the speed of light in air.
- The speed of light in air > the speed of light in water > the speed of light in glass.
- The speed of light in glass > the speed of light in air > the speed of light in water.

For a given lens, what is the height of the image divided by the height of the object ( $\frac{{h}_{i}}{{h}_{o}}$ ) equal to?

- power
- focal length
- magnification
- radius of curvature

Which part of the eye has the greatest density of light receptors?

- the lens
- the fovea
- the optic nerve
- the vitreous humor

What is the power of a lens with a focal length of 10 cm?

- 10 m
^{–1}, or 10 D - 10 cm
^{–1}, or 10 D - 10 m, or 10 D
- 10 cm, or 10 D