§5.2: Biot-Savart Law

Christopher CrawfordPHY 417

2015-01-21

Outline• Magnetic force law

Magnetic field & Lorentz Force – force on two straight wiresForce between current elements – analog of Coulomb’s lawSeparation of field – Lorentz force & Biot-Savart law

• ExamplesStraight wireCircular loopCurrent sheet

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Magnetic field & Lorentz force• Magnetic field definition from torque – electrostatic analogy

• Magnetic field from force on a straight wire – current element

• Lorentz force for currents – TWO right hand rules – parity ?

• Lorentz force for moving particles – or ANY current element

• Relativistic version

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Biot-Savart Law• Coulomb’s Law

• Biot-Savart Law

• Consistency of separation of force into: I’dl’ –> B –> I dl

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Example 5.5: straight wire• Similar to Ch. 2: line charge

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Example 5.6: dipole loop • Closest thing to an electric point charge

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Example: current sheet

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