Question

A cell of emf 8.0 V has an internal resistance of 1.7 ȍ and is connected to a 4.9 ȍ resistor. Find the current in the resistor, the power dissipated in the resistor, and the terminal potential difference across the cell.

Answer 1

emf:

$E=I(r+R)$

where r is internal resistance

$I=E/(r+R)=8/(1.7+4.9)=1.21$ A

power dissipated in the resistor:

$P=I^2R=1.21^2\cdot4.9=7.20$ W

terminal potential difference across the cell:

$U=Ir=1.21\cdot1.7=2.06$ V