Question -
Cell supplies a current of 0.9 A through a 2 ohm resistor and current of 0.3 A through a 7 ohm resistor. What is the internal resistance of the cell?
Options:
A .  0.5 ohm
B .  1 ohm
C .  1.2 ohm
D .  2 ohm
Answer: Option A : A If E the emf of the cell and r its internal resistance then E2+r=0.9 and E7+r=0.3 dividing the two equations we get 7+r2+r=93 r=0.5ohm
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