A rectangular block of copper has sides of length 11 cm, 30 cm, and 45 cm. If th
ID: 1873368 • Letter: A
Question
A rectangular block of copper has sides of length 11 cm, 30 cm, and 45 cm. If the block is connected to a 4.9 V source across two of its opposite faces, find the following.
(a) What is the maximum current the block can carry? [Answer must be in A]
(b) What is the minimum current the block can carry? [Answer must be in A]
I've seen this problem in multiple sites in Chegg, but got different answers with all of them. Can someone help me out to solve this but in a way that I can do it too by using my calculator in case that numbers changes?
Explanation / Answer
R = rho L / A
where rh0 = resistivity of copper = 1.72 x 10^-8 ohm m
(A) for maximum current , R will be smallest possible
{ I = V / R }
and for smallest R, L will be smallest and A will be greatest.
R = (1.72 x 10^-8) ( 0.11) / (0.30 x 0.45)
R = 1.40x 10^-8 ohm
I = V /R = (4.9) / (1.40 x 10^-8) = 3.50 x 10^8 A .....Ans
(B) for minimum current.
R will be greatest.
R = (1.72 x 10^-8) (0.45) / (0.11 x 0.30)
R = 23.45 x10^-8 ohm
I = (4.9) / (23.45 x 10^-8)
I = 0.209 x 10^8 A