General Physics 2 - Magnetism
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?
