Question

Describe the relationship between electricity and magnetism.

Answer 1

@blues can you able to help me with this?

Answer 2

A changing magnetic field induces electrical current in a wire and is the basis for electrical generation. Also an electrical current flowing through a wire creates a magnetic field and is the basis for most motors. In general a changing magnetic field creates an electrical field and a changing electrical field creates a magnetic field

Answer 3

Devilonline: Why is this relationship not perpetual?

Answer 4

It is perpetual...its never ending like if u dont disturb the magnetic field or electric current it wont stop like in motors and generators

Answer 5

it is indeed perpetual.. and thats where james clerk maxwell comes into play.. he saw that they would keep on doing it. and hence he defined his electromagnetic waves!!

Answer 6

Devilonline, how does this not violate conservation of energy?

Answer 7

Cause energy is not lost in the process!

Answer 8

I was implying that it was created. But, I'm assuming it's not so ... where is that additional energy obtained from?

Answer 9

see initially some energy is required to create a disturbance.. infact.. in order to get an electromagnetic wave you need to accelerate charges (oscillating charges).. thats what happens when you switch on your bulb... the filament is heated to a high temperature... which causes the atoms to vibrate and they produce these electromagnetic waves.. so after a while the light diminishes right?..

Answer 10

If you mean as in the light bulb dying then, yes.

Answer 11

No as in becoming dull a bit

Answer 12

exactly.. it dies off.. so the disturbance eventually dies off

Answer 13

No wait ur saying wen we turn on a bulb

Answer 14

Devilonline, are you talking to me or Mashy?

Answer 15

So then like it doesnt die off

Answer 16

Sorry i shud specify...mashy

Answer 17

all waves.. eventually die off right??.. a ripple in water.. doesn't keep on going continuously.. theoretically it should.. but in reality it doesn't.. thats what I am saying!

Answer 18

So the light doesnt diminish the waves do no?

Answer 19

Ok, what about reality prevents that ripple from continuing? Other ripples that cancel the wave out, etc?

So, about an engine, are you saying it would get more and more powerful infinitely if the engine never broke?

Answer 20

Without giving it more energy.

Answer 21

the light DOES diminish... cause if you switch on teh bulb.. and you keep going farther and farther away.. the light becomes dull and finally at one point.. for all practical purposes you can't see the light at all!!

Answer 22

@s3a.. i have no idea what you are saying? :P

Answer 23

Ooohhh!! I get it!! :D

Answer 24

S3a same here i dnt get what u r saying

Answer 25

Sorry lol. Two secs.

Answer 26

"It is perpetual...its never ending like if u dont disturb the magnetic field or electric current it wont stop like in motors and generators "

This implies that if I give a motor some energy, I will never need to give it any more since it will (perpetually) make it on its own so the motor should go on forever until it breaks but, this doesn't seem to be the case with cards. You need to keep burning fuel (or whatever) to feed energy. So what am I missing?

Also, sorry for being difficult to understand. I am presently tired but this topic striked my curiosity.

Answer 27

cars*

Answer 28

That the more electromagnetic energy u need more elcectricity and a stronger magnet u would need otherwise it would have the same magnitude of power...in cars u press the accelerator and it accelerates by getting more power from the battery

Answer 29

Like if u need a constant EMF source

Answer 30

s3a.. you have friction.. if there was no friction.. then what you said is right!!

Answer 31

Mashy, friction with the car parts?

Answer 32

Oh yea eddy currents

Answer 33

No eddy currents....u know what they are??

Answer 34

I don't know what eddy currents are.

Answer 35

What I meant by "car parts" is basically "not tires".

Answer 36

Mashy the friction is cuz of the eddy currents right?

Answer 37

i mean we live in a world comprised of friction.. thats why we need to put in more energy.. !! if there was no friction.. then a car once set into motion.. will keep moving until it hits something :P..

and friction inside car parts, friction between tyres and roads..

even if there was only friction INSIDE car parts.. but not outside.. then also.. once car set in motoin

Answer 38

Mashy also because of eddy currents

Answer 39

Mashy, I didn't understand what you said about if there was friction only INSIDE.

Answer 40

Ok so the bottom line is, energy can be created perpetually but it is lost to friction so the end result is you need to put more energy in manually?

Answer 41

Rather than relying on the "perpetual"ness.

Answer 42

yea yea.. correct .

Answer 43

I think a better word would be "obtained" rather than "created". Would it?

Answer 44

For the energy.

Answer 45

Yesssss!!! I think i got confused about my concepts too by this question lol

Answer 46

Glad, I could do my part lol. :)

Answer 47

Wait which grade r u in s3a?

Answer 48

I already did my first electromagnetic course (before university). Right now, I'm going to 2nd year software engineering.

Answer 49

Non-university level by the way.

Answer 50

For the E&M course.

Answer 51

OMG and im explaining this to u lol no wonder i got confused by ur questions....ohbwait u did ur electromagnetic course but u dont know about eddy currents O.o

Answer 52

Maybe I just don't know them by name.

Answer 53

Did you learn that in the first year undergrad course (US system)?

Answer 54

Eddy currents (also called Foucault currents[1]) are electric currents induced within conductors by a changing magnetic field in the conductor. These circulating eddies of current have inductance and thus induce magnetic fields. These fields can cause repulsive, attractive,[2] propulsion, drag and heating effects. The stronger the applied magnetic field, or the greater the electrical conductivity of the conductor, or the faster the field changes, then the greater the currents that are developed and the greater the fields produced.

Answer 55

Nope olevels (cambridge system)

Answer 56

Well, I don't remember the stuff well and I need to review but is that like getting the intensity of the induced emf?

Answer 57

I don't know the UK system. Do you have a school before University and after High school?

Answer 58

What comes before senior year in highschool?

Answer 59

That just confused me more lol. In Canada, there is high school and then University but in Quebec there is high school --> CEGEP/College --> University

Answer 60

Do you have a middle school like that?

Answer 61

Again, I'm tired right now so sorry if I say stupid things.

Answer 62

No like ok ill make it simple im talking about the 11 and 12th grade

Answer 63

Well, I technically did it in 13th if I remember correctly and I did the waves course before instead of after.

Answer 64

waves, optics, modern physics

Answer 65

Oohk that makes sense now

Answer 66

Yea we do it in the 12th grade

Answer 67

Sorry i meant 11th

Answer 68

Oh, 11th I did kinematics, optics, stuff like that.

Answer 69

Anyways, this was nice but, I have to go fix a computer now so I'm going to go.

Thank you both. @Devilonline and @Mashy

Answer 70

Lol nice working with u lol tc

Answer 71

You too. :) Bye.