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Instructor(s): G. Boyd
PHYSICS DEPARTMENT
EXAM 2
PHY 2005, Summer 2009
Name (print, last first):
July 20, 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 lines 76–80 on the answer sheet 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 the 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) Hand in the answer sheet separately.
Physical Constants:
g = 9.8 m/s2
me = 9.11 × 10−31 Kg
mp = 1.67 × 1027 Kg
e = 1.6 × 10−19 C
constant k in Coulomb’s Law: k = 8.99 × 109 Nm2 /C2
εo = 8.85 × 10−12 C2 /Nm2 , µo = 4π × 10−7 N/A2
1. Given that B =
(1)
µ0 I
what are correct units for µ0 ?
2πR
Tesla meter second
Coulomb
(2)
Tesla meter
Coulomb second
(3)
Tesla meter
Coulomb
(4)
Tesla second
Coulomb meter
(5) none of these
2. A person looking into a mirror 40 cm away sees their face twice as large. What is the focal length and type of mirror?
(1) 80 cm, concave
(2) −80 cm, convex
(3) 120 cm, concave
(4) −40 cm, convex
(5) none of these
3. A G.I.Joeformer is held by a child 20 cm from a convex fun-house mirror. The focal length has magnitude |f | = 8cm.
How far is the image and is it real/virtual, inverted/upright?
(1)
(2)
(3)
(4)
(5)
−5.71, virtual, upright
−13.0, virtual, upright
−5.71, real, upright
−.075, real, inverted
none of these
4. A certain frequency light has wavelength 2 cm. It enters a medium where the effective speed of light is 2 × 108 m/s.
What is its new wavelength?
(1) .013 m
(2) 1.33 m
(3) 1 × 1010 m
(4) 75 m
(5) none of these
5. Two parallel wires are separated by 10 cm. They both carry a current of size 10 Amps but their currents flow in opposite
driections. The force per unit length wire is:
(1) 6.3 × 10−5 N
(2) 6.3 × 10−6 N
(3) 6.3 × 10−7 N
(4) 5.6 × 10−5 N
(5) none of these
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6. A 4.5 cm square loop is being pulled out of a perpendicular magnetic field at 20 cm/s. The induced EMF is 1.37×10−3 V.
What is the field strength (absolute value)?
(1) .15 Tesla
(2) 0.007 Gauss
(4) 1.5 × 10−5 Tesla
(3) 0.00685 Tesla
(5) none of these
7. A student wants to build a circuit with resonant frequency 1.5 × 1010 Hz. The student already has a .5 mH inductor,
what size capacitor is needed?
(1) 2.25 × 10−19 F
(2) 8.88 × 10−18 F
(3) 2.12 × 10−8 F
(4) 4.71 × 103 F
(5) none of these
8. An RC circuit is being used to time something in a totally awesome way. R = 3 × 106 and C = .04µF. How long until
the circuit is about 63 percent charged?
(1) .12 seconds
(2) .75 seconds
(3) 1.333 seconds
(4) .15 seconds
(5) none of these
9. The RMS voltage in scenic country of Germaniranceland is 234 V, what is the maximum voltage that comes out of the
sockets there?
(1) 330 V
(2) 165 V
(3) 234 V
(4) 273 V
(5) none of these
10. We are designing some extremely sensitive equipment which involves a circular loop of radius 20 cm. The earth’s
magnetic field is roughly .5 GAUSS at an angle of 10 degrees with the vertical. If vertical is normal to our loop, what
is the flux due to the earth’s field in our loop?
(1)
(2)
(3)
(4)
(5)
1 × 10−6 TESLA · m2
3.4 × 10−6 TESLA · m2
.0108 TESLA · m2
6.28 × 10−6 TESLA · m2
none of these
11. What is the energy in joules of radiation that has wavelength 10−7 m (ultraviolet light for suntans, melanoma, and the
likes)?
(1) 1.98 × 10−18 J
(2) 3.0 × 10−19 J
(3) .23 × 10−19 J
(4) 2.0 × 10−41 J
(5) none of these
12. A microwave oven generates electromagnetic waves of frequency 2.4 GHz that are reflected by the walls and form standing
waves that heat food as the energy of the waves are absorbed. The standing-wave pattern causes food to be heated
unevenly, with burn marks at the wave peaks. If the distance between the burn marks is 4.8 cm, what is the effective
speed of light inside the food in km/s?
(1) 2.3 × 108
(2) 2.3 × 105
(3) 2.4 × 109
(4) 2.3 × 106
(5) none of these
13. A block of material is found to have a critical angle with respect to air of 56.0◦ . What is its index of refraction?
(1) 1.21
(2) .83
(3) 1.333
(4) 1.41
(5) none of these
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14. A lithium ion of m = 11.6 × 10−27 kg and charge e is shot into a field of strength .045T. What will the radius of its
path be if its speed is 3.6 × 105 m/s?
(1) 0.581 m
(2) .0261 m
(3) 9.2 × 10−20 m
(4) 1.72 m
(5) none of these
15. ndiamond = 2.42 and nice = 1.31. You live in a really, really cold climate and you are asked to marry someone who gives
you a huge ring, but you suspect that your diamond might be ice. In order to test whether or not you have the real deal,
you place the gem onto a block of ice and whip out your laser pointer and protractor. If your beam makes an angle of
30 degrees with respect to the normal in the diamond, then what angle will the beam make with respect to the normal
in the ice block?
(1) 67.4 degrees
(2) 15.7 degrees
(3) 22.6 degrees
(4) 74.3 degrees
(5) none of these