A coil of 15 turns, each of radius 1 centimeter, is rotating at a constant angul

Question

A coil of 15 turns, each of radius 1 centimeter, is rotating at a constant angular velocity w = 300 radians per second in a uniform magnetic field of 0.5 tesla, as shown in the figure above. Assume at time t = 0 that the normal to the coil plane is along the y-direction and that the selfinductance of the coil can be neglected. If the coil resistance is 9 ohms, what will be the magnitude of the induced current in milliamperes?
Simple enough problem, but I'm not getting the right answer. Here's what I'm doing -- tell me where I went wrong.
dB/dt = 2 B0/.5 rev = 600/pi B0 T/s = 300/pi T/s
dphi/dt = dB/dt * A = .03 V
-dphi/dt = -.03 V = EMF
EMF*N/ R = .03V*15 / 9 = 50 mA
Only that's wrong, answer should be a multiple of pi. What happened? (Feel free to start from scratch, ifthat's easier)
Thanks, Alex A coil of 15 turns, each of radius 1 centimeter, is rotating at a constant angular velocity w = 300 radians per second in a uniform magnetic field of 0.5 tesla, as shown in the figure above. Assume at time t = 0 that the normal to the coil plane is along the y-direction and that the selfinductance of the coil can be neglected. If the coil resistance is 9 ohms, what will be the magnitude of the induced current in milliamperes?
Simple enough problem, but I'm not getting the right answer. Here's what I'm doing -- tell me where I went wrong.
dB/dt = 2 B0/.5 rev = 600/pi B0 T/s = 300/pi T/s
dphi/dt = dB/dt * A = .03 V
-dphi/dt = -.03 V = EMF
EMF*N/ R = .03V*15 / 9 = 50 mA
Only that's wrong, answer should be a multiple of pi. What happened? (Feel free to start from scratch, ifthat's easier)
Thanks, Alex

Explanation / Answer

    Given that the number of turns in the coilN = 15 turns     Radius of the coil is r = 1 cm = 0.01m     The angular velocity is = 300rad/s     The magnitude of magnetic field is B =0.5 T      The resistance of the coil is R = 9 --------------------------------------------------------------------       The induced emf is =d /dt                                      = NABsint              themaximum emf is = NAB              Then the induced current is I = /R                                             = NAB / R                                              =---------- A                                           

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.