This exam consists of 28 questions; true-false questions are worth 2
points each, three-choice multiple choice questions are worth 3 points
each, five-choice multiple choice questions are worth 6 points each.
The maximum possible score is 92. The exam period was 90 minutes; the
mean was 68.6; the median was 69. Click here to see
of the formula sheet that came with the exam.
Two thin lenses are separated by 11 cm. Lens #1 is a diverging lens
and its focal length is -2 cm. Lens #2 is a converging lens with 7 cm
focal length. An object (arrow) is located 8 cm to the left of lens #1.
If lens #2 were not present, the image formed by lens #1 would be
(a) 4.1 cm to the left of lens #1.
(b) 1.6 cm to the left of lens #1.
(c) 1.6 cm to the right of lens #1.
(d) 3.5 cm to the right of lens #1.
(e) 4.1 cm to the right of lens #1.
(a) 7.8 cm to the left of lens #1
(b) 3.7 cm to the left of lens #2
(c) 15.8 cm to the right of lens #2
(a) upright relative to the object.
(b) inverted relative to the object.
(a) 0.14 m
(b) 0.32 m
(c) 0.57 m
(d) 0.61 m
(e) 0.89 m
Consider the spherical mirror with focal point f and center C shown in
For the object (arrow) shown in the figure, where will the image
(b) It depends on the focal length of the mirror.
A fiber optic line can transport light over long distances by using
total internal reflection to reflect the light back into the fiber. The
fiber shown has a core (n = 1.67) surrounded by a material of a
different index (n = 1.33).
Inside the fiber, what is the maximum angle θ capture
the light can have and still undergo total internal reflection?
(a) θcapture = 31.8°
(b) θcapture = 37.2°
(c) θcapture = 43.4°
(d) θcapture = 48.7°
(e) θcapture = 54.3°
(b) remain the same.
A light beam travels through three different materials along the path
shown. The index of refraction of the first medium is n1
= 2.1. Only two angles are measured: θ1 =
35°, and θ3 = 49°.
How does the index of refraction of the first medium n1
compare to the index of refraction of the second medium
(a) n1 > n2
(b) n1 = n2
(c) n1 < n2
(a) n3 = 1.4
(b) n3 = 1.6
(c) n3 = 1.8
(a) n2 = 1.1
(b) n2 = 1.2
(c) n2 = 1.3
(a) The index of refraction of the thin lens is larger than that of the thick lens.
(b) The index of refraction of the thin lens is smaller than that of the thick lens.
(c) The index of refraction does not affect the focal length of the lenses.
With unaided vision your professor can focus only on objects which
lie at distances between 3.0 meters and 0.5 meters.
Which type of lens is needed to allow him to see objects beyond 3
(a) | P | = 4.1 diopters
(b) | P | = 1.9 diopters
(c) | P | = 0.50 diopters
Intense white light is incident on a diffraction grating with 500
What is the angular separation between violet (400 nm) and red (700
nm) first-order spectra?
Two thick glass plates (n = 1.5) are stacked at an angle, as shown in
the picture below. The space between the plates is filled with air (n =
1.0). Light of unknown frequency is incident on the plates, and the
first bright spot is observed where the plates are separated by a
distance of 1.7 × 10-7 m.
Calculate the wavelength of the incident light. (Be careful all of
these wavelengths will give bright or dark spots at that distance!)
(a) λ = 340 nm
(b) λ = 453 nm
(c) λ = 680 nm
(a) still a maximum.
(b) a minimum.
(c) neither a maximum nor a minimum.
(a) 103 nm
(b) 140 nm
(c) 185 nm
Monochromatic light (λ = 550 nm) is incident on two slits
separated by a distance 1.3 × 10-4 m. Bright fringes
are observed on a screen at an unknown distance D from the two slits.
The separation between two adjacent bright fringes is 2.5 ×
Calculate the distance D from the slits to the screen.
(a) D = 5.9 m
(b) D = 11.8 m
(c) D = 13.7 m
(b) remain the same.
The waves from a radio station can reach a radio via two different
paths as shown in the diagram to the right. One is a straight line
path, a distance of 30 km. The other is by bouncing off a cloud midway
between the transmitter and the receiver.
Find the minimum height (h) of the cloud that will produce
destructive interference between the direct, and reflected waves.
The wavelength of the wave is 400 meters. You may assume that there is
no phase change upon reflection at the cloud.
(a) h = 1730 m
(b) h = 2140 m
(c) h = 2390 m
(d) h = 2830 m
(e) h = 3520 m
(a) Both lens #1 and lens #2 can produce the same maximum
(b) Lens #1.
(c) Lens #2.