Question

A 70-Ω electrical appliance and a 100-Ω electrical appliance are plugged into the outlets of a house. By what factor will the power used change if an additional 130-Ω electrical device is plugged in?

Answer 1

Answer:

For an additional 130-Ω electrical device, the power used will change by a factor of 0.77.

Explanation:

Power is given as;

P = I²R

Where;

P is the power used due to resistance of the electrical appliance

I is the current passing through the appliance

R is the resistance offered by the appliance

For 70-Ω electrical appliance and  100-Ω electrical appliance, the total power used is;

P = 70I² + 100 I² =  (170I²) W

for an additional 130-Ω electrical device, the new the total power used is;

P = 130I² +  (170I²)  = (300 I²)W

$Change \ in \ power \ used = \frac{I^2(300-170)}{I^2(170)} =0.77$

Therefore, for an additional 130-Ω electrical device, the power used will change by a factor of 0.77.