A light bulb is connected to a 120.0-V wall socket. The current in the bulb depe

Question

A light bulb is connected to a 120.0-V wall socket. The current in the bulb depends on the time t according to the relation I = (0.622 A) sin [(439 rad/s)t]. (a) What is the frequency of the alternating current? (b) Determine the resistance of the bulb's filament. (c) What is the average power delivered to the light bulb?

An electric field is constant at every point on a square surface that is 0.80 m on a side. This field has a magnitude of 6.3 N/C and is oriented at an angle of 35° with respect to the surface, as the drawing shows. Calculate the electric flux Epassing through the surface.

Explanation / Answer

a) frequency of the alternating current = w / 2 pi

= (439) / (2 pi) = 69.87 Hz

b) Irms = Im / sqrt 2 = 0.622 / sqrt 2 = 0.44 A

Resistance = Vrms / Irms = 120 / 0.44

= 272.7 ohms

c)  Average power delivered to the light bulb = Vrms / Irms = 120 * 0.44

= 52.8 W

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