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Unformatted text preview: the bar begins to move, the brightn
the light bulb
is 19.3kg/m3 and its atomic weight is 197 amu. Find the drift speed of the electrons
in a wire with circular cross section of radius 3mm and which is carrying a current of
carrying .1A.
• a. 1.4 ×10−4 m/s
• b. 3.7 ×10−4 m/s
• c. 5.9 ×10−5 m/s
• d. 2.7 ×10−2 m/s
2. An aluminum wire of length 5L and a copper wire of length L have precisely the same
B) × 10−8 Ω −
resistance. A) decreases. of the two materials are: aluminum, 2.8 increases. m and
The resistivity
C) suddenly drops to zero.
D) stays the same.
copper 1.7 × 10−8 Ω − m. What is the ratio of the radius of the copper wire to the
aluminum wire?
• a. .05
• b. .12
• c. .35
• d. .87
3. How long is a wire made from a volume 100 cm3 of copper if its resistance is 8.5 ohms?
The resistivity of copper is 1.7 x 108 Ωm. 2
• a. 7.1 m
• b. 1.7 x 102 m
• c. 2.2 x 102 m
• d. 3.0 x 103 m
4. An electric toaster requires 1 100 W at 110 V. What is t...
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This document was uploaded on 02/26/2014 for the course PHYS 1B at UCSD.
 Winter '07
 BRIANKEATING
 Magnetism

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