Magnetism-Electromagnetism

Equation for magnetic force

F=qvB

B

strength of the magnetic field, measured in teslas

Strength of Earth’s magnetic field

25-65 microteslas

Direction of magnetic force

perpendicular to the magnetic field and the velocity of the particle

Deflection

whenever a particles velocity changes direction, the force exerted on it also changes direction, deflecting it in a circle

Centripetal force

force that only changes an object’s direction, not its speed

Mass spectrometer

used to determine a sample’s atomic composition; sample is vaporized, ions are accelerated by a voltage, ions are moved into magnetic field and deflected; where they land depends on charge and mass

Ampere’s law

used to determine magnetic field of objects; B=(μI)/2πr

Amperian loop

circle with radius r that goes around a current-carrying wire

μ

permeability of free space

Solenoid

multiple circular loops on top of each other; has a magnetic field similar to a bar magnet

Magnetic field in a solenoid

B=μI(N/L)

Teslas

unit for strength of magnetic fields

Michael Faraday

young bookbinder who became interested in electricity after attending public lectures, worked as Humphrey Davy’s lab assistant, studied connection between electricity and magnetism

Humphrey Davy

famed chemist

Christmas Lectures

public lectures at the Royal Institution, tradition started by Faraday; broadcasted by the BBC

Faraday’s Law

moving a magnet near a coil of wire will induce a voltage in the wire; V=−N(ΔΦ/Δt)

Magnetic field flux

Φ; how much magnetic field there is passing through a given area (area of a loop of wire)

Generator

any device that converts mechanical motion into electrical energy

Motor

a device that turns electrical energy into mechanical motion

Lenz’s Law

negative sign in Faraday’s Law; moving magnet turns solenoid into its own magnet, magnetic field created by solenoid will be whatever it needs to be to oppose the external change