Brainiac, Season 1 Episode 4.
Electric Fence Experiment Richard Hammond

School blocks YouTube? Use the file below.

 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

L = .30 m

A = 5.0 x 10-5 m2

Page 4 Reference Table

ρ = 1.72 x 10-8 Ωm

(reference)

 R = 1.72 x 10-8 Ωm(.30 m) 5.0 x 10-5 m2

R = 1.0 x 10-4  Ω

a) How could you alter the dimensions of this wire to reduce the resistance?

R = ρL/A

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)

Rank the wire resistance from least to greatest

June 2017