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Instructor(s): F.E. Dunnam
PHYSICS DEPARTMENT
PHY 2054
Final Exam (SV 21.8–25)
Name (print, last first):
06 August 2009
Signature:
On my honor, I have neither given nor received unauthorized aid on this examination.
YOUR TEST NUMBER IS THE 5-DIGIT NUMBER AT THE TOP OF EACH PAGE.
(1) Code your test number on your answer sheet (use 76–80 for the 5-digit number). Code your name on your
answer sheet. DARKEN CIRCLES COMPLETELY. Code your UFID number on your answer sheet.
(2) Print your name on this sheet and sign it also.
(3) Do all scratch work anywhere on this exam that you like. Circle your answers on this test form. At the end of the
test, this exam printout is to be turned in. No credit will be given without both answer sheet and printout.
(4) Blacken the circle of your intended answer completely, using a #2 pencil or blue or black ink. Do not
make any stray marks or some answers may be counted as incorrect.
(5) The answers are rounded off. Choose the closest to exact. There is no penalty for guessing. If you believe that no correct
answer is listed, leave this item blank!!
(6) Hand in the answer sheet separately.
Useful (??) Constants:
µ0 = 4π × 10−7 Tm/A
²0 = 8.85 × 10−12 C2 /(Nm2 )
c = 3 × 108 m/s
electron charge = −1.6 × 10−19 C
electron mass = 9.11 × 10−31 kg
V=volt
N=newton
J=joule
m=meter
W=watt µ = “micro-” = 10−6
−12
−9
−3
A = ampere “pico” = 10
n = “nano” = 10
m = “milli” = 10
proton mass = 1.67 × 10−27 kg
1. Which one of the following types of electromagnetic radiation travels at the greatest speed in vacuum/free space?
(1) All of these travel at the same speed
(2) Radio waves
(3) Visible light
(4) X rays
(5) Infra-red radiation
2. The sun’s average daily intensity normal to the earth’s surface at Orlando, FL, in August is approximately 400 W/m2 .
What is the value (amplitude) of the electric vector (in V/m) associated with these waves?
(1) 549
(2) 301,600
(3) 400
(4) 388
(5) 150,800
3. Monochromatic light traveling through a plate-glass window (n = 1.5) emerges into the air. In air, the frequency (f)
and the wavelength (λ), compared to their values in the glass, are:
(1) f same, λ greater
(2) both the same
(3) f same, λ smaller
(4) λ same, f greater
(5) λ same, f smaller
4. A transparent glass (n = 1.52) paperweight is a cube measuring 6 cm on an edge. It has a tiny bubble inside it located
3.2 cm from one surface. To an observer looking at this surface, how far below it (in cm) does the bubble appear to be
located?
(1) 2.1
(2) 1.6
(3) 4.9
(4) 6.4
5. Three flat, 4 cm-thick plates of differing refractive indices are
stacked as shown. Monochromatic light is incident in air from
above on the stack at a 30◦ angle with the normal. The angle
(with the normal) at which the ray emerges from the bottom of
the stack in air will be
(1) 30◦
(2) no emergence, due to total internal reflection
(5) 3.95
n=1.2
n=1.4
n=1.6
(3) 60◦
(4) 18◦
(5) none of these
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6. A concave mirror has a radius of curvature of 40 cm. How far from the mirror (in cm) is the resulting image if the image
is inverted and 4 times smaller than the object?
(1) 25
(2) 15
(3) 50
(4) −15
(5) 100
7. Real images formed by a spherical mirror are always:
(1)
(2)
(3)
(4)
(5)
none of these
on the same side of the mirror as the source but closer to the mirror than the source
on the same side of the mirror as the source but closer to the mirror than the focal point
on the same side of the mirror as the source but further from the mirror than the focal point
on the side of the mirror opposite the source
8. An object is placed 150 cm from a screen. An image is formed on the screen when a certain lens is placed between the
two at a distance of 120 cm from the object. Moving only the lens, an image can also be formed on the screen for an
object-to-lens distance (in cm) of
(1) 30
(2) 60
(3) 12.5
(4) 40
(5) 16
9. An erect object is placed on the central axis of a thin lens, further from the lens than the magnitude of its focal length.
The magnification is +0.5. This means that:
(1)
(2)
(3)
(4)
(5)
the
the
the
the
the
image
image
image
image
image
is
is
is
is
is
virtual and erect, and the lens is a diverging lens
real and erect and the lens is a converging lens
real and inverted and the lens is a converging lens
virtual and erect, and the lens is a converging lens
virtual and inverted and the lens is a diverging lens
10. A single converging lens (f = 20 cm) is used to form an enlarged image on a screen 3m from the lens. The upper half of
the lens is then covered with an opaque card, in which case the image on the screen will
(1)
(2)
(3)
(4)
(5)
become less bright
become brighter
be missing its upper half
be missing its lower half
become badly out of focus
11. White light is incident normally on a uniform film of water (n = 1.33) lying on a glass plate (n = 1.56). The 550 nm
wavelength is missing from the reflected light. What is the minimum water film thickness (in nm) required to produce
this effect?
(1) 103
(2) 207
(3) 155
12. Light of wavelength λ is normally incident on a diffraction grating
G. The diffraction pattern on screen S, 4m from the grating, has
a central maximum at P and the first order line appears at Q, 3 m
from P. The distance between adjacent slits in the grating is
(4) 88
(5) 176
Q
(3 m)
incident light
P
(4 m)
S
G
(1) 5λ/3
(2) 3λ/4
(3) 3λ/5
(4) 4λ/5
(5) 5λ/4
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13. Three polarizing sheets are placed in a stack with the polarization
axes (A) of the first and third perpendicular to each other. Unpolarized light is incident on the stack. The beam emerging from the
stack has 1/8 the intensity of the incident beam. What angle must
the polarizing axis of the middle sheet make with that of the first
sheet?
?
A
A
A
I
P1
(1) 45◦
(2) 30◦
(3) 60◦
(4) 57.5◦
P2
P3
(5) impossible
14. An unaided eye has a far point of 2 m. With the proper corrective lens, its near point becomes 30 cm. What was the
near point without the lens?
(1) 26 cm
(2) 35 cm
(3) 2 cm
(4) 19 cm
15. In a two-lens (compound) microscope, the intermediate image is (with respect to the object):
(1)
(2)
(3)
(4)
(5)
real, inverted and enlarged
virtual, erect, and enlarged
real erect, and enlarged
virtual, inverted, and reduced
virtual, inverted, and enlarged
(5) 49 cm