Question

A primary cell has an emf of 1.5 volts, when short-circuited it gives a current of 3 amperes. The internal resistance of the cell is

• A. 4.5 ohm
• B. 2 ohm
• C. 0.5 ohm
• D. $\frac{1}{4.5}$ ohm

Answer 1

The correct option is C 0.5 ohm

$i_{SC}=\frac{E}{r}\Rightarrow 3=\frac{1.5}{r}\Rightarrow r=0.5\Omega$