Electric and Magnetic feilds (1 Viewer)

[Bank$]

Can someone please tell me the EXACT differance between electric and magnetic feilds ??? I have asked so many ppl and they cnt seem to explain it properly

thanks,

 

[jyu]

Can someone please tell me the EXACT differance between electric and magnetic feilds ??? I have asked so many ppl and they cnt seem to explain it properly

thanks,

Electric field strength at a point is the electric force (N) per unit charge (C) at that point.

E = F/Q

Magnetic field strength at a point is the maximum magnetic force (N) per unit length (m) of conducting wire carrying a unit (A) of electric current.

B = F(max)/IL

:wave:

 

[Bank$]

Thanks Jyu that cleared most of my doubts but what I would also like to know is that are magnetic and electric fields independent of each other and more importantly:

What is the difference between magnetic force and electric force?
(In terms of nature and origin)

Thanks in advance

 

[xiao1985]

electric field exert a force on charged stuff (moving or still)

magnetic field excert a force on a moving charged stuff (provides that it it cuts the flux of the magnetic field... ie, charged stuff move perpendicular to the flux direction)


nature: electric field always exert force along the field line, magnetic field always exert force perpendicular to the field line and direction the charged particle is moving

origin: well, not something you need to be concerned with, but magnetic field is generated when a charged particle moves.... electric field you will need to know, arises from existence of a charged substance

also, if a charged substance accelerates, it generates self propagating electric field and magnetic field, ie what we call a photon.

 

[Bank$]

magnetic field excert a force on a moving charged stuff

so is it an electric feild that makes a magnet attrack stuff when still e.g putting a iron object next to a magnet and leting it go and observeing movement of the iron object.

provides that it it cuts the flux of the magnetic field... ie, charged stuff move perpendicular to the flux direction)

if i move soming towards a magnets north pole(in a straight line) it experiences a force but i cnt c how it is travelling perpendicular to the feild lines, pls explain

also when u pass a current through a circuit which is broken with two parallel plates it produces an uniform electric feild between the plates, why ??? and why not a magnetic feild

when u pass a current through a coil it prodcues a magnetic feild and not an electric feild, why ?

the final question for this post

can i think like this ???: "a charged particle exerts an electric force and when it moves aswell as an electric force it exerts a magnetic force

im srry guys but pls bare with me as i learn by fully understanding

thanks so much in advanced

 

[xiao1985]

a) no, firstly, iron filling is not charged... which means, even if you place it in an electric field, it should not experience a non-negligible force. the force arrives from the interaction between the existing magnetic field in the iron filling and the magnet (ie, NS attracts, NN and SS repels)

b) thereotically, if you are moving a charged object towards a north pole, in a parallel fashion, it will not experience a force... I am guess you are saying, say for eg, you move a N pole of a magnetic towards and other N of an other magnet, you feel a repulsion force, why is that, right?! that again, is the interaction between two magnetic fields. Also, a magnetic is uncharged overall.

c) if the circuit is broken it cannot have a current going through them... a current, is something that flows... if it's broken, then it doesn't flow...

the reason why you generate an electric field is because there's a separation of charge... you build up a potential difference at two different poins... effectively, you have a positive charge and a negative charge

d) same as above, just exactly opposite... when you have a coil, you are having a flow of current... a current WILL generate a magnetic field, via right hand screw rule. and in theory it does have an electric field... but it's rather ambiguous and beyond what you need to know for the hsc: the electric field is really what's causing the current to flow... say for eg, the conventional current goes from left of page to right of the page, you can really say there's an electric field going from left to right

as for the final question, you are almost right:

a charged particle creates an electric field... a moving charged particle, in addition to the electric field, creates a magnetic field.

 

[Bank$]

thanks again xiao for clearing that up for me but now i have a query on magnets from what i know a permanent magnet is caused by electron spin lining up what i would like to know is how does this property allow a magnet to pick up something like a paper clip which is not magnetic and just to add u were correct, some of this stuff is way out the scope of the sylabis as i found through internet research.

and from a) u said and iron filling is not charged do u mean no net charge and if so does that mean a stationary charged object will not be affected by a magnetic field what so ever ?

this is a general question: Am i doing the right thing by trying to understand all this or should i just accept it and learn it later in uni ????

 

[xiao1985]

as a fellow science student, i'd encourage you finding the whole truths out... though be weary writing the answer down in an exam... uncalled for truth may hurt..... alot in your mark

iron filling has no net charge... you are right... a stationary CHARGED object should not be affected by the magnetic field... (duh for the UNCHARGED object... it shouldn't experience a force even if it is moving)

as for why a magnet attract metals, metals comprises of unpaired electrons (due to their spins, little magnetic fields as well... however they are aligned randomly, otherwise they'd be a magnet as well) ... when a magnetic approaches (say north pole), the north pole will influence the little unpaired electrons, and forces it to spin in such a way that, the magnetic field it generates has south pole pointing towards the north pole (since it's an attractive force)... and now, you have temporarily created a "magnetic" where the south poles align to make a bigger south pole facing the north pole... and of course, south north attracts, hence magnet attracts metal...

 

[Bank$]

be weary writing the answer down in an exam... uncalled for truth may hurt..... alot in your mark

What u said is very true as this is the same mistake that i commonly make, i manage to kill the multiple choice but do horrible with long response.

what i am thinking now is to write my own notes on these fields to further understand them just for self confidence.

thanks alot especially Xiao and if i have any more questions ill start a new thread

 

[Bank$]

be weary writing the answer down in an exam... uncalled for truth may hurt..... alot in your mark

What u said is very true as this is the same mistake that i commonly make. I manage to kill the multiple choice but do horrible with long response.

what i am thinking now is to write my own notes on these feilds to further understand them just for self confidence.

thanks alot especially Xiao and if i have any more questions ill start a new thread

 

[jyu]

as a fellow science student, i'd encourage you finding the whole truths out... though be weary writing the answer down in an exam... uncalled for truth may hurt..... alot in your mark


as for why a magnet attract metals, metals comprises of unpaired electrons (due to their spins, little magnetic fields as well... however they are aligned randomly, otherwise they'd be a magnet as well) ... when a magnetic approaches (say north pole), the north pole will influence the little unpaired electrons, and forces it to spin in such a way that, the magnetic field it generates has south pole pointing towards the north pole (since it's an attractive force)... and now, you have temporarily created a "magnetic" where the south poles align to make a bigger south pole facing the north pole... and of course, south north attracts, hence magnet attracts metal...

Then why copper and many other metals and non-metals are not attracted by magnets.

By the way, physics is based on theories, not truths.

:wave:

 

[xiao1985]

re ^

i would assume that copper does not have u.p.e.

i don't know the detail, but copper dimer does seem to exhibit a spin coupling at low temperature as i recall, and reduces its magnetism.
non metals are not attracted by magnetic field as their electrons are mostly paired up (with very few exceptions such as oxygen)

as for truths/theory... lol ... you are right... at most it can only be called an attempt to describe the truth....