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

School blocks YouTube? Use the file below.

| Electric_Fence.mov |

 

 

 

 

 

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

 

 

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

 

 

 

 

 

 

 

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