General Physics 2 - Magnetism

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ampere's law

"for any closed loop, the dot product of the magnetic field and the total distance around the loop is equal to the product of the permeability constant and current enclosed by the loop"

lc circuit

"oscillatory circuit" contains an inductor and a capacitor. when a charged capacitor is connected to an inductor, energy oscillates from electrical to magnetic, and back to electrical

lenz's law

"the direction of the induced current is such that its own magnetic field opposes the change that induced it"

Faraday's Law of Electromotive Induction

"the induced electromotive force in a closed loop is equal to the negative times rate of change of magnetic flux inside the loop"

permeability of free space

4π x 10^-7 T*m/A

MAGNETIC FIELD

PALM METHOD - 4 FINGERS

MAGNETIC FORCE

PALM METHOD - PALM

CURRENT

PALM METHOD - THUMB

direction of magnetic field

RHGR - 4 Fingers

direction of the current

RHGR - Thumb

direction of current (v)

RHR - INDEX FINGER

magnetic field

RHR - MIDDLE FINGER

magnetic force

RHR - THUMB

Magnetic Force

a consequence of the electromagnetic force, one of the four fundamental forces of nature, and is caused by the motion of charges

1 T = 1 x 10^4 G

convertion of tesla to gauss

dc circuit

current of constant magnitude

ac circuit

current of magnitude varying with time

inductor

device placed in a circuit to oppose a change in current; that is to maintain, regulate a steady current in that section of the circuit

ac circuit

electrons keep switching direction

change in b (magnetic flux), change in a (area), change in angle, number of coils, time

factors that changes the induced emf

dc circuit

flows in one direction

Cyclotron Formula

formula that denotes the number of rotations that a particle will make

dc circuit

frequency is zero

dc circuit

from cells or battery

ac circuits

from generators and mains

Hans Cristian Oersted

his discover led to the concept of electromagnetism

by exposing it to another magnet with a strong magnetic field

how do u magnetize a demagnetized magnet?

movement changes the magnetic field that changes the magnetic flux. therefore, no movement, no induced emf.

how to change the magnetic flux?

Φ = Max

if angle is 0 or 180 (perpendicular)

Φ = 0

if angle is 90 (parallel)

Φ = less than maximum

if angle is at a certain degree

self-inductance

inductor will be able to oppose a change in electric current flowing by itself

monopole

kind of magnetic pole that do not exist

solenoid

loop of wire or coil

continue on straight toward the north pole again (S to N)

magnetic field line flow inside the magnet

point out of the north pole and then they curve toward the south pole (N to S)

magnetic field line flow outside the magnet

hammering, burning or heating, being exposed to alternating current

methods of demagnetization

dc circuit

move steadily in one direction

circular motion

movement of the charge when placed in a magnetic field

electromagnetism

moving electric charges inducing a magnetic field perpendicular to the flow of current

mutual inductance

need another inductor to induce back emf

Repulsive Force

objects with charge moving in opposite directions have ________ between them

Magnetic Poles

parts of the magnet where the magnetic field is strongest

closer to the source -> stronger magnetic field

relationship of the distance between the source and magnetic field lines

closer -> stronger magnetic field

relationship of the spaces between magnetic field lines

ac circuit

reverses its direction while flowing in a circuit

unlike - attract, like - repel

rules of magnets

ac circuit

safe to transfer over longer city distances and can provide more power

magnetic field lines

series of lines that represent magnetic field, continuous loops

magnetic field

space around the magnet or any other magnetic object where magnetic field/force acts

inductance

tendency of an electrical conductor to oppose a change in the electric current flowing through it. measured in Henry (H)

ac circuit

the frequency of alternating current is 50Hz or 60Hz depending on the country

north and south pole

these poles never separate

dipole

this is always the case for magnetic poles

biot savart law

this law predicts the magnetic field at a point P, a distance r, away from the current I in a wire

Magnetic Flux (Weber - Wb)

total number of magnetic field lines passing through a given coil or area

Magnetic Attraction

two objects containing charge with the same direction of motion have a _________ force between them

permanent, natural, temporary, electromagnets

types of magnets

Hertz

unit named after Heinrich Hertz for frequency

dc circuit

voltage cannot travel very far until it begins to lose energy

demagnetization

wearing out of magnetic properties

no magnetic field exists, no force exists

what happens if the current is turned off?


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