Question

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

• A. 4.5ohm
• B. 2ohm
• C. 0.5ohm
• D. 1/4.5ohm

Answer 1

Answer: (C)

0.5ohm

Answer 2

Short circuit current $i _ { S C } = \frac { E } { r }$

⇒ $r = 0.5 \Omega$