Physics: Resistance and Resistivity

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SR21XXX
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Questions
1)Calculate the resistivity of a wire of resistance 5.0 Ω, if the length of the wire is
2.0 m and the diameter of the wire 0.2 mm. (2 marks)
2) Determine the length of a constantan wire, of resistivity 4.9 × 10−7 Ω m and
diameter 0.1 mm, required to make a coil of resistance 20 Ω. (2 marks)
3a) Calculate the resistance of 10 m of wire of diameter 0.36 mm and resistivity
44 × 10−8 Ω m. (2 marks)
b) Deduce the resistance of another wire of the same material but of half the
length and half the diameter (1 mark)
4) The potential difference across 5.0 m of nichrome wire is 3.2 V and the current
flowing through it is 0.20 A. The resistivity of nichrome is 1.0 × 10−6 Ω m.
Determine the diameter of the wire. (3 marks)
Exam-style question
5) A generator produces 100 kW of power at 500 V. If the power lost in the 800 m
long copper cables connected to the generator is 6% of the power produced,
calculate the diameter of the cable.
Resistivity of copper = 1.6 × 10−8 Ω m
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jduxie4414
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Hey! What exactly are you struggling with? On TSR, we're not meant to share answers to questions but if you post some of your working we can give you some pointers?

Edit: I've moved this thread into the Physics section so hopefully you'll be more likely to get help!

The resistivity equation is R=pl/A, where R is the resistance, p(rho) is the resistivity, l is the length of the conductor and A is it's cross sectional area. Rearranging this equation to make different variables the subject should help you answer the questions!
Last edited by jduxie4414; 1 year ago
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SR21XXX
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#3
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(Original post by jduxie4414)
Hey! What exactly are you struggling with? On TSR, we're not meant to share answers to questions but if you post some of your working we can give you some pointers?

Edit: I've moved this thread into the Physics section so hopefully you'll be more likely to get help!

The resistivity equation is R=pl/A, where R is the resistance, p(rho) is the resistivity, l is the length of the conductor and A is it's cross sectional area. Rearranging this equation to make different variables the subject should help you answer the questions!
thanks so much
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