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Electromagnetism. Magnetic Field Concept Force on a Current-Carrying Conductor Force on a Moving Charge Magnetic Fields due to Currents. The ABCs of Magnets. Questions. What are magnets? Where were the first magnets discovered? What types of materials do they attract?
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Electromagnetism Magnetic Field Concept Force on a Current-Carrying Conductor Force on a Moving Charge Magnetic Fields due to Currents
Questions • What are magnets? • Where were the first magnets discovered? • What types of materials do they attract? • Explain “opposites attract” in terms of magnets. • How did the Chinese make use of magnets? • What benefit(s) do we get out of magnetism that are mentioned in the video?
Magnetic Field • Magnets attract without coming in contact with the objects. How do they do this? • Magnetic field lines • Directions of lines • Earth • Geographic poles • Compass • Magnetic poles
Making Magnets • Current-carrying wires produce magnetic fields • Corkscrew rule or RHR • Solenoid carrying a steady current produces a magnetic field • The solenoid rule
Force on Current-Carrying Wires • Force on a • Mass • Charged mass • Charged moving mass • (Fleming’s) Left-hand Rule • Equation • Magnetic Field Strength (Magnetic flux density)
Example • A straight wire of length 0.25 m carrying a steady current of 4.5 A is placed horizontally in a uniform horizontal magnetic field of strength 85 mT. Calculate the force on the wire due to the magnetic field and the direction of the force if the angle between the wire and the field line is • (a) 90 • (b) 0 • (c) 60
Motors and Meters • The turning effect • Couple • Number of turns • Equation • The moving coil meter • The electric motor
Moving Charges • Force on a moving charge • Circular Motion • Electron Beams • Thermionic emission • Cyclotron