Tuesday, July 28, 2009

Physics problems?

1) A light bulb is connected to a 120V wall socket. The current in the bulb depends on the time(t) according to the relation I=(0.709A)sin[(315Hz)t], where the peak current is 0.709A.


(a) what is the frequency of the alternating current?


(b) determine the resistance of the bulb's filament


(c) what is the average power consumed by the light bulb?





2) One heater uses 343.90W of power when connected by itself to a battery. Another heater uses 236.95W of power when connected by itself to the same battery. How much total power do the heaters use when they are both connected in series across the battery?





3) A coffee cup heater %26amp; a lamp are connected in parallel to the same 120-V outlet. Together, they use a total of 88.15W of power. The resistance of the heater is 606.80 ohms. Find the resistance of the lamp.





4) The heating element in an iron has a resistance of 26.9 ohms. The iron in plugged into a 120V outlet. What is the power dissipated by the iron?

Physics problems?
1a. 50hz


1b


1c. 60W


2. 140 W


3. 223.5


4. 535 W


All numbers are approximate


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