biot-savart law the field produced by a straight wire
Post on 19-Dec-2015
261 views
TRANSCRIPT
Problem 4
Consider a very long (essentially infinite), tightly wound coil with n turns per unit length. This is called a solenoid. Assume that the lines of B are parallel to the axis of the solenoid and non-zero only inside the coil and very far away. Also assume that B is constant inside. Find B inside the solenoid if there is a current i flowing through it.
Problem 3
An infinitely long wire has 5 amps flowing in it. A rectangular loop of wire, oriented as shown in the plane of the paper, has 4 amps in it. What is the force exerted on the loop by the long wire?
An infinitely long, hollow cylindrical wire has inner radius a and outer radius b. A current i is uniformly distributed over its cross-section. Find the magnetic field everywhere.
Chapter 10 Quiz
Faraday’s Law of Induction
The induced EMF in a closed loop equals the negative of the time rate of change of magnetic flux through the loop
dt
dEMF B
dt
drdE B
There can be EMF produced in a number of ways:
• A time varying magnetic field• An area whose size is varying• A time varying angle between and • Any combination of the above
B
Sd
R
From Faraday’s law: a time varying flux through a circuit will induce an EMF in the circuit. If the circuit consists only of a loop of wire with one resistor, with resistance R, a current
R
EMFi
Which way?
Lenz’s Law: if a current is induced by some change, the direction of the current is such that it opposes the change.
dt
drdE B