1) What is the resistance of .30 m length of copper wire that has a cross-sectional area of 5.0 x 10-5 m2?
1) What is the resistance of .30 m length of copper wire that has a cross-sectional area of 5.0 x 10-5 m2?
R = ρL/A
ρ = 1.72 x 10-8 Ωm
L = .30 m
A = 5.0 x 10-5 m2
| R = | 1.72 x 10-8 Ωm(.30 m) |
| 5.0 x 10-5 m2 |
R = 1.0 x 10-4 Ω
Why do large speakers require thick speaker wire?
Large speakers draw a lot of current
a) How could you alter the dimensions of this wire to reduce the resistance?
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To reduce the resistance in a wire you could:
L ?
Shorten
A?
Increase
2) If the length of a wire were halved, how would that change the wires resistance?
R = ρL/A
R, L direct
R would be halved
Cross-sectional Area (A) doubled?
R = ρL/A
R, A inverse
R, halved
3) Which material on your reference table would produce a wire that would allow current to flow the best?
Silver, lowest resistivity
R, L plot for resistor
June 1997
