an electric cell with nominal voltage E has a resistance of 3\Omega connected across it. If the voltage falls to 0.6E, the internal resistance of the cell is
A
1Ω
B
2Ω
C
3Ω
D
4Ω
Verified Correct Answer: B.
Physical Principles & Numerical Solution
IR = 0.6 X I ( R + r )
I X 3 = 0.6 X I ( 3 + r )
3I / 0.6I = 3 + r
5 = 3 + r
r = 2 ohms
Source: Myschool Past Questions Archive (Record #12041)