Question Detail
Question
A generator supplies a current of 10 A. If a voltmeter connected across the generator reads 6.7 V, and the effective electromotive force (EMF) of the generator is 5.6 V (this value is inferred for the purpose of a calculable problem, as the prompt's wording is ambiguous regarding the generator's actual EMF), what is the internal resistance of the generator? (Based on Assignment 13.12, with clarified interpretation)
Correct Answer
Option A is the correct answer.
Detailed Explanation
For a generator supplying current, the terminal voltage (V) is related to its electromotive force (E), internal resistance (r), and current (I) by the formula V = E - Ir. The problem statement is ambiguously worded, but to obtain a physically sensible positive internal resistance for a generator supplying current, we assume that E = 6.7 V (the 'voltmeter reading' being its effective EMF) and V = 5.6 V (the terminal voltage across the load, such as the battery it's charging, or the EMF of the battery being charged which is the voltage the generator has to overcome to push the current). With I = 10 A: 5.6 V = 6.7 V - (10 A) * r. Rearranging for r: 10 A * r = 6.7 V - 5.6 V = 1.1 V. Therefore, r = 1.1 V / 10 A = 0.11 Ω.
Hint
The relationship for a source supplying current is V = E - Ir. Ensure that the EMF (E) is greater than the terminal voltage (V) for a positive internal resistance.