Pls help me with my Resistivity Question in pHysics due tomorrow morning.

[emjez15]

Pls help me..thanks

Homework Statement

17. How long should a copper wire 20 mills in diameter be for it to have a resistance of 5.0Ω?

20. An electric motor draw 10 A from a 240-V source 120 ft away. What is the minimum diameter of the copper wire in mills if the voltage drop is not to exceed 2%?

22. A copper wire 1.0 mm in diameter carries a current of 12 A. Find the potential difference between two points in the wire that are 100m apart.

24. The resistance of a copper wire is 100 Ω @ 20oC. Find its resistance at 0oC and at 80oC

25. An iron wire has a resistance of 2.00 Ω at 0oC and a resistance of 2.46 Ω at 45oC. Find the temperature coefficient of resistivity of the wire

 

[LowlyPion]

What is it you don't understand?

You need to show some effort and identify where you are stuck.

 

[thomate1]

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Hello, I understand that you need help with your resistivity questions in physics. It is important to start by understanding the formula for resistivity, which is p = RA/L, where p is the resistivity, R is the resistance, A is the cross-sectional area of the wire, and L is the length of the wire.

For question 17, you can use the formula to solve for L, which would be L = RA/p. Plug in the given values for R, A, and p to solve for the length of the wire in meters. Remember to convert the given diameter of 20 mills to meters before solving.

For question 20, you can use the formula V = IR, where V is the voltage drop, I is the current, and R is the resistance. Plug in the given values for V and I, and use the calculated value of R to solve for the minimum diameter of the wire in meters.

For question 22, you can use the formula V = IR, where V is the potential difference, I is the current, and R is the resistance. Again, plug in the given values for I and R, and use the calculated value of V to solve for the potential difference in volts.

For question 24, you can use the formula R2 = R1(1 + αΔT), where R2 is the resistance at the new temperature, R1 is the resistance at the initial temperature, α is the temperature coefficient of resistivity, and ΔT is the change in temperature. Plug in the given values for R1 and ΔT, and solve for R2 at the desired temperatures of 0°C and 80°C.

For question 25, you can use the formula α = (R2 - R1)/(R1ΔT), where α is the temperature coefficient of resistivity, R2 is the resistance at the new temperature, R1 is the resistance at the initial temperature, and ΔT is the change in temperature. Plug in the given values for R1, R2, and ΔT to solve for α.

I hope this helps you with your questions. Remember to show your work and double check your units to ensure accurate answers. Good luck with your assignment!