Lightbulb A is marked \"10.0 W 120 v,\" and lightbulb B is marked 100 W 120 V.\"

Question

Lightbulb A is marked "10.0 W 120 v," and lightbulb B is marked 100 W 120 V." These labels mean that each lightbulb has its respective power delivered to it when it is connected to a constant 120-V source. (a) Find the resistance of each lightbulb. (b) During what time interval does 2.00 C pass into lightbulb A? (c) Is this charge different upon its exit versus its entry into the lightbulb? Yes O No Explain. This answer has not been graded yet. (d) In what time interval does 1.30 J pass into lightbulb A? (e) By what mechanisms does this energy enter and exit the lightbulb? Explain.

Explanation / Answer

(a) P = V2/R

R =  V2 / P

RA = 1202 / 10

RA = 1440 Ohms

RB = 1202 / 100

RB = 144 Ohms

(b) We know that Q = I/t

first, let's find the current through bulb A

From ohm's law

V = IR

I = V/R = 120/1440 = 0.08333 AMPS

Then

t = I / Q = 0.08333 AMPS / 2 C

t = 0.041666 sec

(c) The charge is same but it will be at lower potential

(d) P = E/t

t = E/P

t = 1.30 / 10 = 0.13 sec

(e) It enters by electrical energya and leaves by heat energy and radiation

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