Answer: the constant of proportionality is 2.5 ohms
Explanation:
If two quantities are directly proportional, it means that an increase in the value of one quantity would cause a corresponding increase in the other quantity. Also, a decrease in the value of one quantity would cause a corresponding decrease in the other quantity.
Given that Voltage, V is directly proportional to current,I, if we introduce a constant of proportionality, k, the expression becomes
V = kI
If V = 5 volts when I = 2 amps, then
5 = 2k
k = 5/2 = 2.5 ohms