Question

. A one-meter of annealed copper 25 mm in diameter is drawn until its resistance is 40 times the initial resistance. Its diameter afterwards is?

Answer 1

-First is that we need to write the given first so that we will not be confused.

-d1=2.5 cm; R2 is 100 times of r1 so that is R2=100R1; and lastly d2 is missing

-Remember the formula on how to get the resistance that is R=rhoV/A^2

-We need to derive the formula on how to get the d2

- We need to ratio the R2/R1

-Substitute the main formula and then the process of elimination

-Until we arrive to the final formula (see the picture)

- Now we will be using this formula to get the value of d2

-Use your calculator

- Just simple algebra by simply cross multiply and then the fourth root and with that you will arrive at the answer which is 0.7906cm