5The imaging magnet in most MRI machines is of the superconducting type The imaging magnet in most MRI machines is of the superconducting type. The magnet is the most expensive component of the MRI system.
6The behavior of magnetic poles is similar to that oflike and unlike electric charges.
7Surrounding a magnet there is a magnetic field. The direction of the magnetic field at any point in space is the direction indicatedby the north pole of a small compass needle placed at that point.
8The magnetic field lines and pattern of iron filings in the vicinity of a bar magnet and the magnetic field lines in the gap of a horseshoemagnet.
10When a charge is placed in an electric field, it experiences a force, according to
11The following conditions must be met for a charge to experience a magnetic force when placed in a magnetic field:The charge must be moving.The velocity of the charge must have a component that isperpendicular to the direction of the magnetic field.
12Right Hand Rule No. 1. Extend the right hand so the fingers point along the direction of the magnetic field and the thumb points alongthe velocity of the charge. The palm of the hand then faces in thedirection of the magnetic force that acts on a positive charge.If the moving charge is negative,the direction of the force is oppositeto that predicted by RHR-1.
13DEFINITION OF THE MAGNETIC FIELD The magnitude of the magnetic field at any point in space is definedaswhere the angle (0<θ<180o) is the angle between the velocity ofthe charge and the direction of the magnetic field.SI Unit of Magnetic Field:
14Example 1A proton moves perpendicularly to a magnetic field that has a magnitude of 4.20x10-2 T. What is the speed of the particle if the magnitude of the magnetic force is 2.40x10-14 N?
15Example 2If an electron in an electron beam experiences a downward force of 2.0 × 10−14 N while traveling in a magnetic field of 8.3 × 10−2 T west, what is the direction and magnitude of the velocity?
16Example 3A uniform 1.5 T magnetic field points north. If an electron moves vertically downward (toward the ground) with a speed of 2.5 × 107 m/s through this field, what force (magnitude and direction) will act on it?
17Charged particle in an electric field. Charged particle in a magnetic field.
18Does electric force do work on a moving charge? Does magnetic force do work on a moving charge?
19The magnetic force always remains perpendicular to the velocity and isdirected toward the center of thecircular path.
21Example 1A 6.0 m wire carries a current of 7.0 A toward the +x direction. A magnetic force of 7.0 × 10−6 N acts on the wire in the −y direction. Find the magnitude and direction of the magnetic field producing the force.
22Example 2A wire 1.0 m long experiences a magnetic force of 0.50 N due to a perpendicular uniform magnetic field. If the wire carries a current of 10.0 A, what is the magnitude of the magnetic field?
23Example 3The magnetic force on a straight 0.15 m segment of wire carrying a cur- rent of 4.5 A is 1.0 N. What is the magnitude of the component of the magnetic field that is perpendicular to the wire?
24Example 4The magnetic force acting on a wire that is perpendicular to a 1.5 T uniform magnetic field is 4.4 N. If the current in the wire is 5.0 A, what is the length of the wire that is inside the magnetic field?