Question

The EMF of an electric cell with
internal resistance of 2 Ω is 3.5V. If a
current of 0.5A flows when
a resistor is connected across it. Find the
resistance of the resistor.

Answer 1

$I=\frac{E}{R+r}\to R=\frac{E-Ir}{I}=\frac{3.5-0.5\cdot 2}{0.5}=5(\Omega)$