3. Magnetism and Electromagnetism Flashcards
the place where magnets where discovered
Magnesia
the one who discovered magnets
Magnese
the direction of the magnetic field lines (magnetism) is from north to south but within the magnet the direction is from south to north
Magnetism
small magnet created by the electron orbit
Magnetic Dipole
an accumulation of many atomic magnets with their dipoles aligned
Magnetic Domain
is the ability of a material to attract the lines of magnetic field intensity
Magnetic Permeability
CLASSIFICATION OF MAGNETS
- Naturally occurring magnets
- Artificially induced permanent magnets
- Electromagnets
consists of wire wrapped around an iron core
Electromagnets
do not react to magnetic source (wood)
Nonmagnetic
weakly repelled from the magnet (silver and gold)
Diamagnetic
highly attracted to magnets (iron)
Ferromagnetic
weakly attracted to magnet (contrast media in MRI)
Paramagnetic
the degree to which a material can be magnetized
Magnetic Susceptibility
MAGNETIC LAWS
- Every magnet, no matter how small, has two poles: north and south
- Like magnetic poles repel and unlike magnetic poles attract
- Ferromagnetic material can be made magnetic when placed in an external magnetic field
- The force between poles is proportional to the product of the magnetic pole strengths divided by the square of the distance between them
Unit for Magnetic Strength
SI unit: Tesla (T)
Conventional unit: Gauss (G)
One tesla (SI Unit; T) = _____ gauss (Conventional unit; G)
10000 gauss
is the force associated with electrons in motion
Electromagnetism
made the Voltaic Pile
Alessandro Volta
proved that electricity can produce magnetism
Hans Oersted
a coil of wire
Solenoid
a ferromagnetic material wrapped in a coil of wire
Electromagnet
proved that magnets can induce electricity
Michael Faraday
Faraday’s experiment. When the switch in the primary circuit is closed, the ammeter in the secondary circuit deflects momentarily. The emf induced in the secondary circuit is caused by the changing magnetic field through the secondary coil
Faraday’s Law of Induction
electric current will be induced to flow in a circuit if some part of that circuit is in changing magnetic field
Faraday’s Law
THE MAGNITUDE OF THE INDUCED CURRENT DEPENDS ON THE FOLLOWING FOUR FACTORS:
- The strength of the magnetic field
- The velocity of the magnetic field as it moves past the conductor
- The angle of the conductor to the magnetic field
- The number of turns in the conductor (the higher turns more electricity
created the Lenz’ law
Heinrich Lenz
induced current flows in a direction such that it opposes the action that induced it
Lenz’ Law
2 TYPES OF INDUCTION
- Self-induction
2. Mutual induction
the induction of an opposing EMF in a single coil by its own changing magnetic field
Self-Induction
the process of inducing a current flow through a secondary coil
Mutual Induction
Changes mechanical energy into electrical energy
Electric Generator
In ________, a coil of wire is placed in a strong magnetic field between two poles of a magnet
electric generator
changes electrical energy into mechanical energy
Electric Motor
energy is supplied to a series of wire loops
Direct Current Motor
energy is supplied to the external magnets
Induction Motor
The force between poles is ______ to the product of the magnetic pole strengths divided by the square of the ______ between them
proportional,
distance
