Download presentation
Presentation is loading. Please wait.
Published byEileen Burke Modified over 9 years ago
1
Today4/23 Magnetic Induction Review HW Questions? Exam 4/24 Force and motion of charged particles B-fields due to wires Force and Torque on current loops Forces from currents (like 4/16 Wires 2) Induced current (like 4/17)
2
Magnetic Induction The current only flows while: the B-field is changing the ring is moving the magnet is moving It’s all about a “changing” B field!!! Look at whether the # of field lines are increasing or decreasing
3
Force on Current Loops Ch 21: Force/Torque arises from a battery operated loop in a static B-field. Ch 22: Current in loops “induced” by a “changing” external field. The loop then reacts as in Ch 21. In fact, battery operated loops resist the changing field caused by themselves! Called “Self Induction” see 22.8
4
Faraday’s & Lenz’z Law E = - tt is the # of field lines inside loop Lenz’s Law Loop “Voltage” can change in many ways: changing B-field changing loop area changing loop angle changing B-field angle This is the “equation” you will see on the exam
5
E = - tt Using Identify initial field direction Identify final field direction Determine direction of the “change” Use Lenz’s law to determine B-field due to the current induced around the loop Use RHR #2 to find direction of induced current
6
Energy Considerations It takes energy to push current around a loop Therefore, forces arising from induced currents must always serve to retard (or slow down) the object
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.