Download Optics Practice

Optics Practice
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. A light ray in air is incident on an air-to-glass boundary at an angle of 30.0º and is refracted in the glass at an
angle of 21.0º with the normal. Find the index of refraction of the glass.
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2. A beam of light in air is incident on the surface of a rectangular block of clear plastic (n  1.49). If the
velocity of the beam before it enters the plastic is 3.00  108 m/s, what is its velocity inside the block?
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3. If the speed of light through an unknown liquid is measured at 1.80  108 m/s, what is the index of refraction
of this liquid? (c  3.00  108 m/s)
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4. When the reflection of an object is seen in a plane mirror, the distance from the mirror to the image depends
on:
a. the wavelength of light used for viewing.
b. the distance from the object to the mirror.
c. the distance of both the observer and the object to the mirror.
d. the size of the object.
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5. If a man wishes to use a plane mirror on a wall to view both his head and his feet as he stands in front of the
mirror, the required length of the mirror:
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6. A concave mirror forms a real image at 25.0 cm from the mirror surface along the principal axis. If the
corresponding object is at a 10.0-cm distance, what is the mirror's focal length?
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7. Which of the following best describes the image of a concave mirror when the object's distance from the
mirror is less than the focal point distance?
a. virtual, upright and magnification greater than one
b. real, inverted and magnification less than one
c. virtual, upright and magnification less than one
d. real, inverted and magnification greater than one
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8. A convex mirror with focal length of 20 cm forms an image 12 cm behind the surface. Where is the object
located as measured from the surface?
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9. When the reflection of an object is seen in a convex mirror the image:
a. will always be real.
b. will always be virtual.
c. may be either real or virtual.
d. will always be enlarged.
____ 10. Parallel rays of light that hit a concave mirror will come together:
a. at the center of curvature.
b. at the focal point.
c. at a point half way to the focal point.
d. at infinity.
____ 11. For a diverging lens with one flat surface, the radius of curvature for the curved surface is 20.0 cm. What
must the index of refraction be so that the focal length is 15.0 cm?
____ 12. An image of an object is formed using a convex lens, the image being 15 cm past the lens. A second lens is
placed 25 cm past the first lens and another image is formed, this time 10 cm past the second lens. Which of
the following statements is always true?
a. Both of the lenses have positive focal lengths.
b. The first lens is diverging and the second is converging.
c. The first lens is converging and the second is diverging.
d. None of the above statements is true.
____ 13. An object is placed 25 cm to the left of a lens of focal length 20 cm. 75 cm to the right of this lens is a plane
mirror. Where does the final image form?
____ 14. A rainbow is a result of:
a. different color droplets of water.
b. dispersion.
c. interference.
d. the Huygens Effect.
____ 15. If a virtual image is formed along the principal axis 10 cm from a concave mirror with the focal length 15 cm,
what is the object distance from the mirror?
____ 16. If a virtual image is formed 10.0 cm along the principal axis from a convex mirror of focal length -15.0 cm,
how far is the object from the mirror?
____ 17. A convex mirror with a focal length of 20 cm forms an image 15 cm behind the surface. If the object height
is 1.2 cm what is the image height?
____ 18. An object is held at a distance of 12 cm from a convex mirror creating an image that is 1/3 the object size.
What is the focal length of the mirror?
____ 19. Ellen places an object 40.0 cm from a concave lens. If a virtual image appears 10.0 cm from the lens on the
same side as the object, what is the focal length of the lens?
____ 20. Two thin lenses with 10.0-cm focal lengths at are mounted at opposite ends of a 30.0-cm long tube. An object
is located 45.0 cm from one end of the tube. How far from the opposite end is the final image?
____ 21. What is the image distance of an object 1.00 m in front of a converging lens of focal length 20.0 cm?
____ 22. When an image is inverted compared to the object, it is also:
a. virtual.
b. reversed left to right.
c. enlarged.
d. diminished.
23. A nearsighted person can see up to 45 cm in front of her. What type of lens, and what power, would
correct her vision?
24. A farsighted person can see no closer than 200 cm. What type of lens, and what power, would correct
her vision?