Question 1

The figure is a scaled diagram of an object and a converging lens surrounded by air. Only one focal point, F, of the lens is shown. 
-The index of refraction of this lens is 1.51 for red light and 1.53 for blue light. Blue light is focused at the point F. Which one of the following statements is true concerning the focal point for red light?

Accepted Answer

A) It is also at F. 
B) It is very close to D. 
C) It is very close to the lens. 
D) It is to the left of and close to F. 
E) It is to the right of and close to F.

Question 2

The system is immersed in a fluid other than air that has an index of refraction that is larger than that of the lens. Which one of the following statements is true concerning this new situation?

Accepted Answer

A) The image will be real. 
B) The image will be inverted. 
C) The image will be enlarged relative to the object. 
D) The image will be formed on the same side of the lens as the object. 
E) The lens may act as a diverging lens or a converging lens depending on the location of the object.

Question 3

The figure shows a point source of unpolarized light at A inside a uniform transparent crystal. The ray AO in the crystal strikes the plane surface SS' making an angle of 30° with the normal. This angle is the critical angle for transmission into air. 
-Which one of the following statements is true concerning this situation?

Accepted Answer

A) When the angle of incidence is equal to the Brewster angle, the angle of refraction is 13°. 
B) When the angle of incidence is equal to the Brewster angle, the angle of refraction is 63°. 
C) When the angle of incidence is equal to the Brewster angle, the angle of refraction is 42°. 
D) Since the Brewster angle is less than the critical angle, there is no refraction when the angle of incidence is equal to $\theta$B. 
E) Since the Brewster angle is greater than the critical angle, there is no refraction when the angle of incidence is equal to $\theta$ B.

Question 4

Without his contact lenses, Mr. Chong can focus from 0.80 m to infinity. What refractive power of the lenses does he require for normal reading (0.25 m from the eyes)?

Accepted Answer

A) 1.25 diopters 
B) 2.75 diopters 
C) 4.00 diopters 
D) 5.25 diopters 
E) -5.25 diopters

Question 5

What is the frequency of light that has a wavelength in water of 788 nm if the refractive index for this light is 1.33?

Accepted Answer

A) 3.76 × 1014 Hz 
B) 5.00 × 1014 Hz 
C) 6.65 × 1014 Hz 
D) 2.86 × 1014 Hz 
E) 9.52 × 1014 Hz

Question 6

Blue light with a wavelength of 425 nm passes from a vacuum into a glass lens; and the index of refraction is found to be 1.65. The glass lens is replaced with a plastic lens. The index of refraction for the plastic lens is 1.54. In which one of the two lenses does the light have the greatest speed and what is that speed?

Accepted Answer

A) glass, 2.28 × 108 m/s 
B) plastic, 2.13 × 108 m/s 
C) glass, 1.82 × 108 m/s 
D) plastic, 1.95 × 108 m/s 
E) The speed of the blue light is the same in the vacuum and both lenses; and it is 2.99 × 108 m/s.

Question 7

A scuba diver shines a flashlight from beneath the surface of water (n = 1.33) such that the light strikes the water-air boundary with an angle of incidence of 37°. At what angle is the beam refracted?

Accepted Answer

A) 31° 
B) 53° 
C) 48° 
D) 65° 
E) 90°

Question 8

When an object is placed 15 cm from a lens, a virtual image is formed. Which one of the following conclusions is incorrect?

Accepted Answer

A) The lens may be a convex or concave. 
B) If the image is upright the lens must be a diverging lens. 
C) If the image is reduced, the lens must be a diverging lens. 
D) If the lens is a diverging lens, the image distance must be less than 15 cm. 
E) If the lens is a converging lens, the focal length must be greater than 15 cm.

Question 9

When certain light rays pass from a vacuum into a block of an unknown material, the measured index of refraction of the material is 3.00. What is the speed of light inside the block?

Accepted Answer

A) 9.9 × 106 m/s 
B) 4.8 × 107 m/s 
C) 1.0 × 108 m/s 
D) 1.9 × 108 m/s 
E) 2.9 × 108 m/s

Question 10

The figure is a scaled diagram of a an object and a converging lens. The focal length of the lens is 5.0 units. An object is placed 3.0 units from the lens as shown. 
-The object has a height of 1.5 units. What is the approximate height of the image?

Accepted Answer

A) 2.0 units 
B) 1.2 units 
C) 5.0 units 
D) 3.8 units 
E) 9.8 units

Question 11

A beam of light that consists of a mixture of red, green and violet light strikes a prism (surrounded by air) as shown. Indices of refraction for this prism for the various colors are indicated in the table. An observer is located to the right of the prism as shown.  
-Which physical phenomenon is illustrated by the fact that the prism has different refractive indices for different colors?

Accepted Answer

A) Doppler effect 
B) dispersion 
C) diffraction 
D) total internal reflection 
E) interference

Question 12

Complete the following statement: The term dispersion refers to the fact that the index of refraction of certain materials

Accepted Answer

A) depends on the Brewster angle. 
B) depends on the wavelength of light. 
C) depends on the angle of incidence. 
D) depends on the intensity of light. 
E) depends on the polarization of light.

Question 13

The moon is observed using a telescope that has an objective lens with a focal length of 3.0 m and an eyepiece with a focal length of 6.0 cm. What is the angular diameter of the moon if the earth-moon distance is 3.85 × 108 m and the diameter of the moon is 3.48 × 106 m?

Accepted Answer

A) 0.36 rad 
B) 0.45 rad 
C) 0.72 rad 
D) 0.90 rad 
E) 1.4 rad

Question 14

The table lists the index of refraction for various substances at 20 °C for light with a wavelength of 589 nm in a vacuum. Through which substance will light with a vacuum wavelength of 589 nm travel with the greatest speed?

Accepted Answer

A) fused quartz 
B) crown glass 
C) ethyl alcohol 
D) carbon tetrachloride 
E) crystalline quartz

Question 15

Light is incident at the Brewster angle on a plastic plate in air. The angle of refraction is 35.0°.
-Determine the Brewster angle.

Accepted Answer

A) 35.0° 
B) 55.0° 
C) 46.5° 
D) 43.5° 
E) 82.3°

Question 16

Light propagates from soda lime glass (n = 1.518) into Pyrex glass (n = 1.473). Determine the critical angle for this situation.

Accepted Answer

A) 13.99° 
B) 45.86° 
C) 52.48° 
D) 65.22° 
E) 76.01°

Question 17

The leg of a spider is 0.2 cm long. When viewed through a microscope, a person with a near point of 25 cm sees an image 2 m long located 10 m away. What is the angular magnification?

Accepted Answer

A) 25 
B) 50 
C) 100 
D) 250 
E) 1000

Question 18

An object is placed 6.5 cm from a thin converging lens with a focal length of 14 cm. Which one of the following statements is true concerning the image?

Accepted Answer

A) The image is virtual and 6.0 cm from the lens. 
B) The image is virtual and 12 cm from the lens. 
C) The image is real and 3.0 cm from the lens. 
D) The image is real and 6.0 cm from the lens. 
E) The image is real and 12 cm from the lens.

Question 19

A certain type of glass is used in making flat-panel computer monitors. For light with a wavelength in air of 656.3 nm, the refractive index of the glass is nA = 1.5160. For light with a wavelength in air of 435.8 nm, nB = 1.5290. Determine the difference, $\lambda$A- $\lambda$B, in their wavelengths inside the glass.

Accepted Answer

A) 147.9 nm 
B) 156.0 nm 
C) 220.5 nm 
D) 268.4 nm 
E) 293.1 nm

Question 20

A beam of light that consists of a mixture of red, green and violet light strikes a prism (surrounded by air) as shown. Indices of refraction for this prism for the various colors are indicated in the table. An observer is located to the right of the prism as shown.  
-Which physical phenomenon is illustrated by the fact that the observer will not see all three colors of light?

Accepted Answer

A) Doppler effect 
B) dispersion 
C) diffraction 
D) total internal reflection 
E) interference

Exam 26: The Refraction of Light: Lenses and Optical Instruments

The system is immersed in a fluid other than air that has an index of refraction that is larger than that of the lens. Which one of the following statements is true concerning this new situation?

Without his contact lenses, Mr. Chong can focus from 0.80 m to infinity. What refractive power of the lenses does he require for normal reading (0.25 m from the eyes) ?

What is the frequency of light that has a wavelength in water of 788 nm if the refractive index for this light is 1.33?

A scuba diver shines a flashlight from beneath the surface of water (n = 1.33) such that the light strikes the water-air boundary with an angle of incidence of 37°. At what angle is the beam refracted?

When an object is placed 15 cm from a lens, a virtual image is formed. Which one of the following conclusions is incorrect?

When certain light rays pass from a vacuum into a block of an unknown material, the measured index of refraction of the material is 3.00. What is the speed of light inside the block?

The figure is a scaled diagram of a an object and a converging lens. The focal length of the lens is 5.0 units. An object is placed 3.0 units from the lens as shown. -The object has a height of 1.5 units. What is the approximate height of the image?

Complete the following statement: The term dispersion refers to the fact that the index of refraction of certain materials

The moon is observed using a telescope that has an objective lens with a focal length of 3.0 m and an eyepiece with a focal length of 6.0 cm. What is the angular diameter of the moon if the earth-moon distance is 3.85 × 10⁸ m and the diameter of the moon is 3.48 × 10⁶ m?

Light is incident at the Brewster angle on a plastic plate in air. The angle of refraction is 35.0°. -Determine the Brewster angle.

Light propagates from soda lime glass (n = 1.518) into Pyrex glass (n = 1.473) . Determine the critical angle for this situation.

The leg of a spider is 0.2 cm long. When viewed through a microscope, a person with a near point of 25 cm sees an image 2 m long located 10 m away. What is the angular magnification?

An object is placed 6.5 cm from a thin converging lens with a focal length of 14 cm. Which one of the following statements is true concerning the image?