# Problems3_2010 - b points F and G All five resistances are...

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Problem set 3, Physics 205; Fall 2010. 1. A copper wire 2 mm in diameter carries a 4 A current. Determine the current density in the wire and the drift velocity of the electrons. Assume that each copper atom contributes one free electron. Hint: you may need some additional parameters of copper. 2. During operation, the effective resistances of a toaster, a microwave oven and an electric frying pan are 20 Ohm, 25 Ohm and 15 Ohm, respectively. If the three are all plugged into a 115 V electrical outlet, what is the total current? What is the total power delivered to these three appliances? 3.   In the figure below find the equivalent resistance between a) points F and H and
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Unformatted text preview: b) points F and G. All five resistances are 5 Ω. 4. What is the current in the 18 Ohm resistor in the figure below? What is the current in the 12Ohm resistor? Please determine the directions of currents as well. What is the power dissipated in the 4.5 Ohm resistor? What is the equivalent resistance of the circuit shown? 5. An RC circuit has EMF =12.0V, R=14 k Ω and C=3.8 μ F. How long does it take for energy stored in the capacitor to reach 75% of its maximal value? Ω 18 Ω 25 Ω 5 . 4 V . 6 Ω 12...
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