Chapter 4 Flashcards
The lines of flux run ______ the magnet AND ______ the magnet
Through/Outside
The stronger the magnetic field the _____ lines of flux
More
Lines of flux(force) flow N to S ____ the magnet and S to N ____ the magnet
Outside/Through
Example of a natural magnet
Lodestone
Example of a artificial magnet
Alnico (Aluminum, Nickle, Cobalt)
Electromagnet temporary produced by moving electric
Current
any flow of current produces a _____ field
Magnetic
When current stops ______ collapses
Magnetic Field
Law of Magnetism: Repulsion-Attraction
Like poles repel, unlike poles attract
Law of Magnetism: Inverse Square Law
Two magnetic fields directly proportional to magnitude.
Inversely Proportional to square of distance
Law of Magnetism: Magnetic Poles
Magnet has two poles no matter how divided poles continue to exist
highly permeable, greatly susceptible to induction
EX: ALNICO
Ferromagnetic
Low permeability, Weak attraction
EX: Platinum, Aluminum
Paramagnetic
Weakly repelled by all magnetic fields
EX: Beryllium, bismuth
Diamagnetic
Not affected by magnetic fields
EX: Wood, Glass, rubber
Nonmagnetic
Responsible for findings of Deflection of a compass/magnetic field
Hans Oersted
Factors governing effectiveness of solenoids & Electromagnet
- Diameter’
- Length
- Current
Discovered magnetic lines of force & wire must have motion relative to each other to induce an electrical current
Micheal Faraday
Ways to create motion
- Move the conductor
- Move magnetic lines of force
- Vary the magnetic flux
Faraday’s First Law of ______
Electromagnetics
Factors regulating strength of induced current
- Strength of magnetic field
- Speed motion between lines of force & conductor
- Angle magnetic lines of force & conductor
- Number of turns in the conducting coil
Lenz’s ______ Law of Electromagnetics
Second
Induced currents oppose any _____ change
Flux (Force)
Who is responsible for Mutual Induction
Faraday
mutual induction involves _______ & _____ coils
Primary & Secondary
Self-Induction has to do with
Alternating current
A generator is a device that converts mechanical energy to _______ energy
Chemical
AC current ______ permits circuit to remain stationary while armature rotates, connects to one end of armature wire
Generator
DC current _______ Single ring, divided in half; each end of wire connected to half of commutator ring
Generator
Motors are the same as generators but in _______
reverse
A transformer is _______ coils placed near one another
Two
Voltage is increased from primary to secondary
Step-up transformer
Voltage is decreased from primary to secondary
Step-down transformer
Formula for Transformer law
Vs/Vp=Ns/Np
