What happens if you cut a bar magnet in half? Do you obtain one magnet with two south poles and one magnet with two north poles? The answer is no: Each half of the bar magnet has a north pole and a south pole. Likewise, the south pole of magnets is attracted to the geographic South Pole of Earth. The magnetic south pole of Earth’s magnet is at the geographic North Pole, so the north pole of magnets is attracted to the North Pole, which is how the north pole of magnets got their name. For example, the poles of the bar magnet shown in Figure 20.2 are where the paper clips are concentrated.įigure 20.5 Earth can be thought of as containing a giant magnet running through its core. A magnetic pole is the part of a magnet that exerts the strongest force on other magnets or magnetic material, such as iron.
These areas are called the poles of a magnet. When humans first discovered magnetic rocks, they likely found that certain parts of these rocks attracted bits of iron or other magnetic rocks more strongly than other parts. Magnetic rocks found in Magnesia, which is now part of western Turkey, stimulated interest during ancient times. The earliest records date back to ancient times, particularly in the region of Asia Minor called Magnesia-the name of this region is the source of words like magnet. Solution Set F/l= 0 I 1 I 2 /2 L F A /l= 5.83 x 10 -5 N/m 90 F B /l=3.37 x 10 -5 N/m -60 F C /l=3.People have been aware of magnets and magnetism for thousands of years. F/L = mg/L =1.18 x 10 -3 N/m 0 I 1 I 2 /2 L = 1.18 x 10 -3 N/m I 2 = 15 Aĭefinitions Ampere current flowing in each of the two long parallel conductors 1 m apart, which results in a force of exactly 2 x 10 -7 N/m of length of each conductor. A second parallel wire 20 cm below it must carry how much current I 2 so that it doesn’t fall due to gravity? The lower wire is a homogenous wire with a mass of 0.12 g per meter of length. Magnetic field profile of 2 parallel current carrying wiresĪmpere’s Experiment B 1 = 0 I 1 /2 L F= 0 I 1 I 2 l/2 LĮxercise B 1 = 0 I 1 /2 L F/l= 0 I 1 I 2 /2 LĮxample Suspending a current with a current A horizontal wire carries a current I 1 =80 A dc.
Direction of Magnetic field is determined by corkscrew method Īmpere’s Law Used to determine the magnetic field yielded by current-carrying wire Ampere’s law states that the product B and length of line segment around any closed path equals µ 0 times the net current through the area enclosed by the path. 27.17Īpplications of motion of charged particles Velocity Selector Particles of a specific speed can be selected from the beam using an arrangement of electric and magnetic fields called a velocity selector. Motion of charged particles in a magnetic field Fig. Motion of charged particles in a magnetic field Magnetic Force on Moving Charge The magnetic force is always perpendicular to v a particle moving under the action of a magnetic field alone moves with a constant speed. Grip and Hand Rules Out of the Page In to the Page Magnetic Force on Moving Charge Moving charged particles are deflected in magnetic fields Right-Hand Rule Units of Magnetic Fields SI units: tesla, T 1 tesla = 1 T = 1 N/A The magnetic force F m acting on a positive charge q moving with velocity v is perpendicular to both F m and the magnetic field B. Magnetic interactions can be described as: A moving charge or a current creates a magnetic field in the surrounding space (in addition to its electric field) The magnetic field exerts a force F m on any other moving charge or current that is present in the field. Magnetic Force Like poles repel, opposite attract An object that contains iron but is not itself magnetized is attracted by either pole of a permanent magnet. Magnetic Fields A force field that denotes the area in which the non-contact force of permanent magnets or current carrying conductors can exert their influence Fields are concentrated at the poles Same properties with Electric field lines except that there is no magnetic monopole
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