Ph126 Spring 2008 Lecture #8 Magnetic Fields Produced by Moving Charges. Prof. Gregory Tarl é [email protected] Last Lecture: Magnetic Forces. Moving charges can experience forces in magnetic fields: Magnitude: Direction: Right-Hand Rule Magnetic force does no work on the moving charge
Ph126 Spring 2008Lecture #8Magnetic Fields Produced by Moving Charges
Prof. Gregory Tarlé
Magnetic Field B
What direction is the force this wire feels because of the magnetic field?
angle between I and B
The two forces on the loop have equal magnitude but they are opposite in direction.
A square loop carries a current I and pivots without friction about the z-axis. A uniform magnetic field B points in the +x direction, and the loop initially makes an angle θ with the x-z plane. The torque on the loop is clockwise.
N = number of turns of wire
The loop tends to rotate such that its normal becomes aligned with the magnetic field
Increases with current, falls off with distance
Two identical parallel long straight wires carrying a current I stand a distance r apart. Which of the following statements is false?
Two parallel long straight wires carrying currents I and 2I stand a distance r apart. Which of the following statements is false?
The force is attractive if the currents are in the same direction and repulsive otherwise
the two wires generate magnetic fields that pull one another toward each other Newton’s 3rd Law.
Current flowing in a loop of wire creates a magnetic field
Current loop can be imagined to be a phantom bar magnet
At center of circular loop
number of turns
number of turns per unit length
net current passing through surface bounded by path
Same as before!