Question 1

Which of the following lens types shown in the image are diverging lenses? Select all that apply.

Accepted Answer

Plano-concave

Question 2

A lens is thinner at the center than at the edges. Which of the following terms describe this lens? Select all that apply.

Accepted Answer

Concave lens

Question 3

A convex lens has a focal length $$f. If an $$object is placed at a distance $$2f$$ from the lens, what is the image distance from the lens?

Accepted Answer

$$f$$

Question 4

If the magnification of an image is negative, then, compared to the object, the image is:

Accepted Answer

Inverted

Question 5

A thin beam of light enters a thick plastic sheet from air at an angle of $$48.0^\circ$$ with the normal and continues in the sheet at an angle of $$35.5^\circ$$ with the normal. What is the index of refraction of the plastic? Use Snell's Law: $$n_1$$ \sin \$$theta_1$$ = $$n_2$$ \sin \$$theta_2.$$

Accepted Answer

$$1.36$$

Question 6

Which of the following statements about the image formed by a single diverging lens are true? Select all that apply.

Accepted Answer

The image is always upright.

Question 7

A cell phone is placed $$40\ \mathrm{cm} in $$front of a converging lens with a focal length of $$20\ \mathrm{cm}. $$How far is the image of this phone from the lens? Use the thin lens equation: $$\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}.$$

Accepted Answer

$$40\ \mathrm{cm}$$

Question 8

A coin is $$12\ \mathrm{cm} in $$front of a converging lens with focal length $$4.0\ \mathrm{cm}. $$Where is the image?

Accepted Answer

$$8.0\ \mathrm{cm}$$ behind the lens

Question 9

A wrench is placed at $$30\ \mathrm{cm} in $$front of a diverging lens with a focal length of magnitude $$10\ \mathrm{cm}. $$What is the magnification of the wrench? Use $$m = -\frac{d_i}{d_o}.$$

Accepted Answer

$$-0.25$$

Question 10

Which of the following scenarios will result in total internal reflection? (Assume $$n_{	ext{air}} = 1$$, $$n_{	ext{water}} = 1.33.)$$

Accepted Answer

Light shines from water into air at an incident angle of $$60^\circ$$

Question 11

A magnifying glass is held $$5.0\ \mathrm{cm} in $$front of a newspaper and produces a magnification of $$+1.5. If $$the image height is $$9.0\ \mathrm{mm}$$, what is the height of the object?

Accepted Answer

$$6.0\ \mathrm{mm}$$

Question 12

A pool of water has a depth $$D = 3\ \mathrm{m}$$ and width $$L = 4\ \mathrm{m}. A $$laser is shone from the bottom left corner to the center of the pool surface. What is the angle of incidence at the water surface? (Assume the laser travels in a straight line from the bottom corner to the center of the surface.)

Accepted Answer

$$\arctan\left(\frac{3}{2}\right)$$

Question 13

Which of the following best describes the image formed by a plane mirror?

Accepted Answer

Virtual and upright

Question 14

A person is nearsighted and their far point is $$60\ \mathrm{cm}. $$What is the focal length of the corrective contact lens needed?

Accepted Answer

$$-60\ \mathrm{cm}$$

Question 15

A thin lens has a focal length of $$+5\ \mathrm{cm}. An $$object $$6\ \mathrm{cm}$$ tall is placed $$15\ \mathrm{cm}$$ from the lens. What is the image distance? Use $$\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}.$$

Accepted Answer

$$7.5\ \mathrm{cm}$$

Question 16

Which of the following is true about the image formed by a single converging lens? Select all that apply.

Accepted Answer

None of the above choices are correct.

Question 17

A plano-convex lens is used as a magnifying glass. What type of image does it form when the object is within the focal length?

Accepted Answer

Virtual and upright

Question 18

A beam of light enters air from water. The angle of refraction will be:

Accepted Answer

Greater than the angle of incidence

Question 19

A plano-concave lens is used in a laser pointer to spread the beam. What is the sign of its focal length?

Accepted Answer

Negative

Guided Study: Lens Types and Identification

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