SAT Physics Subject Test

Chapter 14 Optics

Chapter 14 Review Questions

See Chapter 17 for solutions.

  1. What is the wavelength of an X-ray whose frequency is 1.0 × 1018 Hz?

(A) 3.3 × 10–11 m

(B) 3.0 × 10–10 m

(C) 3.3 × 10–9 m

(D) 3.0 × 10–8 m

(E) 3.0 × 1026 m

  2. In Young’s double-slit interference experiment, what is the difference in path length of the light waves from the two slits at the center of the first bright fringe above the central maximum?

(A) 0

(B) λ

(C) λ

(D) λ

(E) λ

  3. A beam of light in air is incident upon the smooth surface of a piece of flint glass, as shown

If the reflected beam and refracted beam are perpendicular to each other, what is the index of refraction of the glass?




(D) 2

(E) 2

  4. When green light (wavelength = 500 nm in air) travels through diamond (refractive index = 2.4), what is its wavelength?

(A) 208 nm

(B) 357 nm

(C) 500 nm

(D) 700 nm

(E) 1,200 nm

  5. A beam of light traveling in medium 1 strikes the interface to another transparent medium, medium 2. If the speed of light is less in medium 2 than in medium 1, the beam will

(A) refract toward the normal

(B) refract away from the normal

(C) undergo total internal reflection

(D) have an angle of reflection smaller than the angle of incidence

(E) have an angle of reflection greater than the angle of incidence

  6. If a clear liquid has a refractive index of 1.45 and a transparent solid has an index of 2.90 then, for total internal reflection to occur at the interface between these two media, which of the following must be true?

incident beam originates in

at an angle of incidence greater than

(A) the solid


(B) the liquid


(C) the solid


(D) the liquid


(E) Total internal reflection cannot occur.


  7. An object is placed 60 cm in front of a concave spherical mirror whose focal length is 40 cm. Which of the following best describes the image?

Nature of image

Distance from mirror

(A) Virtual

  24 cm

(B) Real

  24 cm

(C) Virtual

120 cm

(D) Real

120 cm

(E) Real

240 cm

  8. An object is placed 60 cm from a spherical convex mirror. If the mirror forms a virtual image 20 cm from the mirror, what’s the magnitude of the mirror’s radius of curvature?

(A) 7.5 cm

(B) 15 cm

(C) 30 cm

(D) 60 cm

(E) 120 cm

  9. The image created by a converging lens is projected onto a screen that’s 60 cm from the lens. If the height of the image is  the height of the object, what’s the focal length of the lens?

(A) 36 cm

(B) 45 cm

(C) 48 cm

(D) 72 cm

(E) 80 cm

10. Which of the following is true concerning a bi-concave lens?

(A) Its focal length is positive.

(B) It cannot form real images.

(C) It cannot form virtual images.

(D) It can magnify objects.

(E) None of the above



electromagnetic (EM) spectrum




visible light



γ-rays (gamma rays)




central maximum

diffraction gratings

incident beam

angle of incidence

reflected beam

angle of reflection

transmitted beam

angle of refraction

law of reflection

index of refraction

Snell’s law



critical angle

total internal reflection (TIR)


plane mirrors



spherical mirror

center of curvature

radius of curvature


focal point



focal length

paraxial rays

concave mirror

convex mirror

ray tracing

mirror equation

magnification equation

converging lens

real focus

diverging lens

virtual focus

optical center


For the test, be sure you are familiar with the following concepts from this chapter.

·        Light is a type of electromagnetic wave.

·        The electromagnetic spectrum is a categorization of electromagnetic waves by their frequency or wavelength.

·        Interference can be constructive or destructive.

·        Young’s double-slit interference experiment shows the results of interference.

·        Reflection and refraction

·        Dispersion of light

·        Total internal reflection

·        Mirrors

·        Plane mirrors

·        Spherical mirrors

·        Ray tracing for mirrors

·        Use equations to answer questions about the image reflected in a mirror.

·        Thin lenses

·        Ray tracing for lenses

·        Use equations to answer questions about the image viewed through the lens.