# Chapter 21 - Chapter 21: MAGNETIC FIELD AND MAGNETIC FORCES...

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Unformatted text preview: Chapter 21: MAGNETIC FIELD AND MAGNETIC FORCES 1. Magnetism 2. Magnetic Field and Magnetic Force 3. Motion of Charged Particles in a Magnetic Field 4. Mass Spectrometers 5. Magnetic Force on a Current-Carrying Conductor 6. Force and Torque on a Current Loop 7. Magnetic Field of a Long, Straight Conductor 8. Force between Parallel Conductors 9. Current Loops and Solenoids 10.Magnetic Field Calculations 11.Magnetic Materials COLLEGE PHYSICS, Part II MAGNETISM Magnetism is a field of physics that is as important as the field of electricity. Actually, electricity and magnetism are tightly interrelated and together constitute the field of electromagnetism. Magnetism can be described as the property of certain materials to attract and repel the same or other materials. These materials are intrinsically magnetic, i.e. possess constant, permanent magnetic properties. These magnetic properties can be transferred from a magnet to an initially non-magnetic material. Similar poles (i.e., S and S, or N and N) repel each other, while unlike poles (S and N) attract. Every permanent magnet necessarily has two poles, called N and S, which tend to orient toward the North and the South poles of the earth, respectively. Magnets, like electric charges, can interact at a distance, implying that each magnet creates a magnetic field felt by another magnet. This also implies that the earth itself is a magnet, as shown in the next slide. The N and S poles are indivisible companions, i.e., unlike positive and negative electric charges, you cannot have a S pole or a N pole separately. Earth’s geographic north pole is close to its magnetic south pole, and the geographic south pole is close to the magnetic north pole. Earth’s magnetic field is created by electric current in its core composed of molten metal. Magnetic fields and magnetic forces are closely related to moving charges. Electric current in a wire creates magnetic field that can cause deflection of the compass needle. Conversely, a moving magnet can cause electric current in a wire. Furthermore, changing current in one loop of wire can cause current in another loop . MAGNETIC FIELD AND MAGNETIC FORCE A magnet creates a magnetic field at all points of the surrounding space. The magnetic field is a vector quantity and is denoted by the symbol B . The magnetic field exerts a magnetic force F on any permanent or induced magnet, including any moving charge or electric current . A magnetic field can be presented by field lines that are tangent to the vector B at all points. The lines point from the N to the S pole. The density of the lines is proportional to the strength of the magnetic field. The field lines never intersect. Magnetic Force A moving charge creates a magnetic field . Therefore, a pre-existing magnetic field exerts a force upon a moving charge. The magnetic force F exerted upon a moving charge is determined by: a)the magnitude of the charge q , b)the magnitude of the field B...
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## This note was uploaded on 10/04/2011 for the course PHY 2054 taught by Professor Zmudskyy during the Spring '08 term at University of Central Florida.

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Chapter 21 - Chapter 21: MAGNETIC FIELD AND MAGNETIC FORCES...

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