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A 40 W lightbulb plugged into a 120V line lights up. What resistance would the lightbulb have to have?
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7 votes
A 40 W lightbulb plugged into a 120V line lights up. What resistance would the lightbulb have to have?

User Madani
by
6.3k points

1 Answer

6 votes

P=40 W

U=120 V

R=?

P=U*I

I=U/R

P=U²/R

R=U²/P

R=120²/40

R= 360 Ω

User Arika
by
6.1k points
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