A 80 electrical appliance and a 90 electrical appliance are

A 80- electrical appliance and a 90- electrical appliance are plugged into the outlets of a house. By what factor will the power used change if an additional 140- electrical device is plugged in?

Solution

Intially net resistance= (80*90)/(80+90)

=42.35 ohms

power= V^2/R

=V^2/42.35 ohms

Net resistance after adding 140 ohms is

= (140*42.3)/(140+42.3)

   =32.51

Final power= V^2/32.51

Power wiil increase in factor of =42.35/32.51

=1.3

It increases by 1.3 factor.