78. * A student in a physics lab investigates the opera- tion of an AC generator. She collects data on the emf of the generator as a function of time (Figure 25-76). The generator consists of a 200-turn coil that is spun in a strong magnetic field. The coil has a cross-sectional area of 25.0 cm². (a) Determine the frequency, f (Hz), of the generated current. (b) Determine the frequency, f (Hz), and the angular frequency, w (rad/s), of the rotation of the coil. (c) Find the magnitude of the magnetic field. (ALI) 3 10.0 0.0 -10.0 DAAN t(s)

78. * A student in a physics lab investigates the opera- tion of an AC generator. She collects data on the emf of the generator as a function of time (Figure 25-76). The generator consists of a 200-turn coil that is spun in a strong magnetic field. The coil has a cross-sectional area of 25.0 cm². (a) Determine the frequency, f (Hz), of the generated current. (b) Determine the frequency, f (Hz), and the angular frequency, w (rad/s), of the rotation of the coil. (c) Find the magnitude of the magnetic field. (ALI) 3 10.0 0.0 -10.0 DAAN t(s)

Physics for Scientists and Engineers, Technology Update (No access codes included)

9th Edition

ISBN:9781305116399

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter31: Faraday’s Law

Section: Chapter Questions

Problem 31.1OQ: Figure OQS1.I is a graph of the magnetic flux through a certain coil of wire as a function of time...

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When a wire carries an AC current with a known frequency, you can use a Rogowski coil to determine the amplitude Imax of the current without disconnecting the wire to shunt the current through a meter. The Rogowski coil, shown in Figure P30.8, simply clips around the wire. It consists of a toroidal conductor wrapped around a circular return cord. Let n represent the number of turns in the toroid per unit distance along it. Let A represent the cross-sectional area of the toroid. Let I(t) = Imax sin t represent the current to be measured. (a) Show that the amplitude of the emf induced in the Rogowski coil is Emax=0nAImax. (b) Explain why the wire carrying the unknown current need not be at the center of the Rogowski coil and why the coil will not respond to nearby currents that it does not enclose. Figure P30.8
An N-turn circular wire coil of radius r lies in the xy-plane (the plane of the page), as in Figure P20.10. A uniform magnetic field is turned on, increasing steadily from 0 to B0 in the positive z-direction in t seconds. (a) Find a symbolic expression for the emf, , induced in the coil in terms of the variables given. (b) looking down on at the xy-plane from the positive z-axis, is the direction of the induced current clockwise or counterclockwise? (c) If each loop has resistance R, find an expression for the magnitude of the induced current, I.
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Two rectangular loops of wire lie in the same plane as shown in Figure OQ31.11. If the current I in the outer loop is counterclockwise and increases with time, what is true of the current induced in the inner loop? More than one statement may be correct, (a) It is zero, (b) It is clockwise, (c) It is counterclockwise, (d) Its magnitude depends on the dimensions of the loops, (e) Its direction depends on the dimensions of the loops.
An N-turn circular wire coil of radius r lies in the xy-plane (the plane of the page), as in Figure P20.10. A uniform magnetic field is turned on, increasing steadily from 0 to B0 in the positive z-direction in t seconds. (a) Find a symbolic expression for the emf, , induced in the coil in terms of the variables given. (b) looking down on at the xy-plane from the positive z-axis, is the direction of the induced current clockwise or counterclockwise? (c) If each loop has resistance R, find an expression for the magnitude of the induced current, I.
(a) A car generator turns at 400 rpm when 1he engine is idling. Its 300-turn, 5.00 by 8.00 cm rectangular coil rotates in an adjustable magnetic field 50 that it can produce suf?cient voltage even at low rpms. What is the field strength needed to produce a 24.0 V peak emf? (b) Discuss how this required field strength compares to those available in permanent and electromagnets.
What is the value of the magnetic flux through the coil in Figure 23.56 (b) due to the wire?
Figure OQS1.I is a graph of the magnetic flux through a certain coil of wire as a function of time during an interval while the radius of the coil is increased, the coil is rotated through 1.5 revolutions, and the external source of the magnetic field is turned off, in that order. Rank the emf induced in the coil at the instants marked A through K from the largest positive value to the largest-magnitude negative value. In your ranking.