Magnetism and Electromagnetism Flashcards

Flashcards about Magnetism and Electromagnetism

Poles of a Magnet

Magnets always have both a north and south pole; cutting a magnet in half results in two magnets, not isolated poles.

Magnetic Pole Interactions

Like poles repel each other, while unlike poles attract each other.

Compass

A suspended magnet that aligns itself with the Earth's magnetic field, pointing towards the magnetic south pole (geographic north pole).

Induced Magnetism

Magnetism is induced by aligning magnetic domains within a material.

Temporary Magnets

Temporary magnetism induced in some metals when they are brought close to a magnet.

Magnetic Field

The region surrounding a magnet where magnetic forces are exerted; also produced by a charged particle in motion.

Magnetic Field Lines

Magnetic field lines leave the north pole and enter the south pole.

Magnetic Force on a Charged Particle

A charge moving through a magnetic field experiences a force. F = qvB

Tesla (T)

Unit of magnetic field strength; 1 Tesla = 10,000 Gauss.

Magnetic Force on Current-Carrying Wires

A force exerted on a wire carrying a current within a magnetic field.

Magnetic Force Equation

F = B I L; determines the magnitude of the magnetic force on a straight segment of wire.

Magnetohydrodynamics

Magnetohydrodynamics (MHD) is the study of the dynamics of electrically conducting fluids.

Spiraling Electrons

Occurs when electrons spiral along magnetic field lines.

Magnetic Levitation

Method where objects are suspended using magnetic fields.

Induced EMF

A magnetic field can give rise to an electric field.

Electric Field Generation

A conductor moving relative to a magnetic field generates an electric field.

Current Induction

Current induced by moving a magnet inside coils.

Electromagnetic Induction

A rotating coil in a magnetic field induces an alternating emf (voltage), which produces an alternating current (ac).

Faraday's Law

When a conductor cuts magnetic flux lines, an electromotive force (emf) is produced.

Faraday’s Conclusions

Relative motion between a conductor and a magnetic field induces an emf in the conductor. The magnitude of the emf is directly proportional to the rate at which the conductor cuts magnetic flux lines and the number of turns of the conductor crossing the flux lines.

Variables in Induced EMF Equations

emf = voltage (V), N = number of turns, = change in flux in Webers (Wb), A = area (m^2), B = magnetic field (T)

Transformer

A device used to increase or decrease an AC voltage.

Step-up vs Step-down Transformer

If the number of turns of wire in the primary is greater than in the secondary, then the voltage in the secondary is lower than in the primary and the transformer is a step-down transformer. If the number of turns in the primary is less than the secondary, then the voltage in the secondary is higher than in the primary and the transformer is a step-up transformer.

Transformer Equation Variables

V is voltage in volts (V), I is current in amperes (A) and N is number of turns.

Power in Transformers

Power remains the same between primary and secondary coils in a transformer.

Power Transmission and Transformers

Transformers are used to step-up voltage for long distance transmission and step-down voltage for local distribution.