Compared to an ideal battery by what percentage does the bat

Compared to an ideal battery, by what percentage does the battery\'s internal resistance reduce the potential difference across the 20 ohm resistor in the figure Express your answer using two significant figures.

Solution

Iold = E/Req_old = 15/(30) = 0.5 A

Voltage across 20 ohm = 20*0.5 = 10 V

Inew = E/Req_new = 15/31

Voltage across 20 ohm = 20*15/31 = 9.6774 V

% change = (10-9.6774)*100)/(10) = 3.226 %