Physics 72: Magnetic Field

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Magnetic Field and Magnetic Forces

J. Manuel Physics 72 1st Sem AY13-14

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Fundamental nature of Magnetism

Magnetism Magnetic Field Magnetic Field Lines and Magnetic Flux Motion of Charged Particles in Magnetic Field Magnetic Force on a Current-Carrying Conductor Force and Torque on a Current Loop

Interaction of moving electric charges

Magnetic forces arise in two stages:
1. Moving charge or a collection of moving charges produces a magnetic field.
2. Current or moving charge responds to this magnetic field and so experiences a magnetic force.
J. Manuel Physics 72 1st Sem AY13-14 2

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Objective

Magnetism Magnetic Field Magnetic Field Lines and Magnetic Flux Motion of Charged Particles in Magnetic Field Magnetic Force on a Current-Carrying Conductor Force and Torque on a Current Loop

1. Describe the interaction between poles of magnets

J. Manuel Physics 72 1st Sem AY13-14

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Magnetism Magnetic Field Magnetic Field Lines and Magnetic Flux Motion of Charged Particles in Magnetic Field Magnetic Force on a Current-Carrying Conductor Force and Torque on a Current Loop

Magnetic phenomena
1st observed at least 2500 years ago in fragments of magnetized iron ores in Magnesia

Magnetized iron ores

Permanent magnets

N: North pole

S: South pole

J. Manuel Physics 72 1st Sem AY13-14

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S: South pole N: North pole

Magnetism Magnetic Field Magnetic Field Lines and Magnetic Flux Motion of Charged Particles in Magnetic Field Magnetic Force on a Current-Carrying Conductor Force and Torque on a Current Loop

J. Manuel Physics 72 1st Sem AY13-14

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S: South pole N: North pole

Magnetism Magnetic Field Magnetic Field Lines and Magnetic Flux Motion of Charged Particles in Magnetic Field Magnetic Force on a Current-Carrying Conductor Force and Torque on a Current Loop

Either pole of a bar magnet attracts an unmagnetized object that contains iron.
J. Manuel Physics 72 1st Sem AY13-14 6