The intensity of a lightbulb with a resistance of 130 ohms is controlled by conn

Question

The intensity of a lightbulb with a resistance of 130 ohms is controlled by connecting it in series with an inductor whose inductance can be varied from L=0 to L=Lmax This "light dimmer" circuit is connected to an ac generator with a frequency of 60.0 Hz and an rms voltage of 120 V

What is the average power dissipated in the lightbulb when L=0 P= 110W

The inductor is now adjusted so that L=Lmax . In this case, the average power dissipated in the lightbulb is one-fourth the value found in part A. What is the value of Lmax ?

Lmax=____________H

Please answer in 'H'

Explanation / Answer

a)

P = V2/R = 120*120/130 = 111 W

b)

P = V2/Z2 R

>>> Z = RV2/P = 1(130*120*120/(110.77/4)) = 260 0hm

L = (Z^2 - R^2) = (260*260-130*130) = 225 H

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