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Unformatted text preview: Equation Sheet for Midterm Exam 2 Electric current dt dq i = Ohms law R V i = The resistance of a wire with length L and area A is R = L/A where = resistivity. Resistors in series n eq R R R R + + + = 2 1 Resistors in parallel n eq R R R R 1 1 1 1 2 1 + + + = Power. The power supplied by an emf device is P emf = i V emf . The power dissipated in a resistor is P = i V = i 2 R (Joules law). RC circuit with emf device. When the capacitor is being charged, [ ] RC t e emf CV t q / 1 ) ( = ; when the capacitor is discharging, RC t e q t q / ) ( = . The time constant is = RC . (Recall C = q/V .) The magnetic force on a charged particle sin magnitude qvB q = = B v F A charged particle in a uniform magnetic field moves on a circular trajectory, in accord with Newtons second law: mv 2 /r = qvB . The magnetic force on a straight length of current carrying wire B L F = i Magnetic dipoles . Torque = B ; potential energy = ...
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 Fall '07
 Gade
 Current, Energy, Potential Energy

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