Unformatted text preview: Physics 2760 Recitation 10/21/2008 1. A rectangular coil of N = 80 turns, each of width a = 20 cm and length b = 30 cm is located in a magnetic field of magnitude B = 0.8 T directed into the page, with only half of the coils in the region of the magnetic field. The resistance of the coil is R = 30 Ω. Find the magnitude and direction of the induced current if the coil is moved with a speed of 2 m/s A) to the right, B) up, and C) down. Problem 1 Problem 3 Problem 2 2. The figure shows a circuit containing a resistor and an uncharged capacitor. Pointing into the plane of the circuit is a uniform magnetic field B. If the magnetic field increases in magnitude with time, which plate of the capacitor (top or bottom) becomes positively charged? 3. A coil of 15 turns and radius 10.0 cm surrounds a long solenoid of radius 2.00 cm and 103 turns per meter. If the current in the solenoid changes as I = 5 sin(120t), find the induced emf in the 15‐turn coil as a function of time. 4. Consider a current I = 0.5 A that flows in a plane rectangular current loop with height a = 4.00 cm and horizontal sides b = 2.00 cm. The loop is placed into a uniform magnetic field B of magnitude 3 T, in such a way that the sides of length a are perpendicular to B , and there is an angle θ = 30° between the sides of length b and B , as shown in the figures. a) Calculate the magnetic moment of the current loop. b) Calculate the net torque of the current loop due to the interaction of the current with the magnetic field. c) Calculate the change in potential energy of the coil‐magnetic field system when the coil rotates from θ = 30° to θ = 90°. 5. A 40‐turn circular coil (radius = 4.0 cm, total resistance = 0.20 Ω) is placed in a uniform magnetic field directed perpendicular to the plane of the coil. The magnitude of the magnetic field varies with time as given by B = 0.50 sin(10 πt) T where t is measured in s. What is the magnitude of the induced current in the coil at 0.10 s? Can you determine the direction of the induced current? ...
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 Spring '08
 kozstin
 Physics, Resistance, uniform magnetic field

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