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Electricity and Magnetism
Chapter 5
Great Idea:Electricity and magnetism are two different aspects of one force—the
electromagnetic force
Chapter Outline
• Nature’s Other Forces• Magnetism• Batteries and Electric Circuits• Connections Between Electricity and Magnetism
• Electrical Effects from Magnetism
Nature’s Other Forces
Static Electricity
• Newton’s first law• Greeks’ observations
– Electrical charge
• Electricity– Static electricity– Properties
Static Electricity
Two Kinds of Electrical Charges
Science in the Making
• Benjamin Franklin and the electrical charge
The Movement of Electrons
• Atomic structure• Electrical charge
– Positive– Negative
• Behavior
Electrons Removed from Hair
Coulomb’s Law
• Coulomb– Experiments
• Coulomb’s Law:
– Force is related to charge and distance
• 1 Coulomb = 6.3 x 1018 electrons
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The Electrical Field
• The force felt by a charge located at a particular point
An Electrical Field Surrounding a Positive Charge
Magnetism
Magnetism
• Magnetic force• William Gilbert
– Dipole magnet– Like repels, unlike attracts
• Magnetic field
A Compass Needle and Earth
The Curving Lines of a Magnetic Field
A Bar Magnet and Its Dipole Field
The Aurora Borealis
The Science of Life
• Magnetic navigation
Pairs of Poles
• No isolated magnetic poles
Batteries and Electric Circuits
The Science of Life
• Luigi Galvani and life’s electrical force
What was behind Frankenstein?
Batteries and Electrical Current
• Electrical current– Flow of charged particles
• Battery– Alessandro Volta– Converts chemical energy to kinetic energy
Electric Circuits
• Electric circuit– Unbroken path of material carrying electricity
– Electrical conductor
• Circuit– Source– Closed path– Device to use electrical energy
Electrical Circuits
Multimeter
Ohm’s Law
• Flow of electricity– Ampere
•1 amp = 1 coulomb/sec– Voltage
•Amount of power in circuit– Electrical resistance
•Ohm
Ohm’s Law – cont.
• Ohm’s Law– Current is directly proportional to voltage and inversely proportional to resistance
– Equation: V = I x R
• Load– Equation: P = I x V
Lightning Strikes
Terms Relating to Electric Currents
The Science of Life
• The propagation of nerve signals
Two Kinds of Electric Circuits
• Series circuit vs. parallel circuit
Connections between Electricity and Magnetism
Magnetic Effects from Electricity
• Oersted– Magnetic field created by electrical charges
• Electromagnet• Magnetic monopole
– Do not exist– Arrangement of electrical charges
Schematic Drawing of an Electromagnet
Electromagnets inside the Disk Drive of a Computer
Technology
• The Electric Motor
The Science of Life
• Magnetic resonance
Electrical Effects from Magnetism
Electrical Effects from Magnetism
• Michael Faraday– Electromagnetic induction– Electrical fields and currents can be produced by changing magnetic fields
• Electric generator
Electromagnetic Induction
Electric Generator
Science in the Making
• Michael Faraday