(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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.)

2. Relevant equations

See below.

3. 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

Thanks.

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# Homework Help: Power and Circuit

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