How many 90-W, 120-V light bulbs can be connected to a 20-A, 120-V circuit without tripping the circuit breaker? (Note: This description of a light bulb gives the power it dissipates when connected to the stated potential difference; that is, a 25-W, 120-V light bulb dissipates 25 W when connected to a 120-V line.)
The Attempt at a Solution
P_total = I*V = 25 W*120 V = 2400 W
On 120 V line, a 90 W, 120 V bulb has a dissipation of 90 W?
Number_bulbs = 2400 W/90W = 26.7 bulbs
So maximum is 26 bulbs?
As a check, compare current values?
I = P_total/V = 26 bulbs(90 W)/(120 V) = 19.5 A, where 19.5 A < 20.0 A