Question

in an electrical circuit, the current passing through a conductor varies inversely with the resistance. Suppose that when the current is 5A, the resistance is 20 ohms. What is the current when the resistance is 25 OHMs?

Answer 1

first set up a regular proportion:
5a/x = 20 ohms/ 25 ohms

Because the problem says the current varies inversely you would flip only one side of the proportion:
5A/xA = 25 ohms/ 20 ohms

cross multiply:
100 = 25x ohms

Divide by 25:

x = 4A

Answer 2

I = k(1/R), where I current, R is resistance and k is a constant

given: I = 5, R = 20
5 = k(1/20)
k = 100
I = 100(1/R)

so when R = 25
I = 100(1/25) = 4