PhysicsLAB: 2010 Form B

AP Free Response Question
2010 Form B - B4

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In the circuit above, the battery of emf

is connected to two long, straight, parallel wires, which in turn are connected to four resistors with resistances given in the figure above. Assume that any other resistances in the circuit are negligible. Express all algebraic answers to the following parts in terms of the given quantities and fundamental constants.

	(a) Derive an expression for the total resistance of the circuit.

	(b) Derive an expression for the power dissipated in this circuit.

Assume that any magnetic fields result only from the currents in the two long wires.

	(c) What is the direction of the magnetic field, if any, at point P, which is in the plane of the page? Explain your reasoning.

	(d) What is the direction of the force, if any, on the bottom wire due to the current in the top wire? Explain your reasoning.

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