EMF, Current and Electric/Magnetic fields

In summary: In other words, what is happening is that the voltage is being created, even though you can't see the magnet moving.2. Also with the conductor in an external magnetic field, since current is induced by voltage,do electrons flow from one side of the rod to another? So is there current even if there's no 'circuit', furthermore does the rod become positively charged in one side and negative in the other?Yes, electrons do flow from one side of the conductor to the other. And, because there's no potential difference, there's also no current.3. As a motor spins, back emf is induced, to eventually result in NET VOLTAGE of zerobut how is there
  • #1
michojek
25
0
Hi, I've been trying to understand electricity... and series of questions came into my mind..

1. I know if i move a conductor in an external magnetic field, it induces EMF, but
I don't really understand INDEPTH how CHANGE in MFlux induces EMF?
I think something to do with EF and MF...

2. Also with the conductor in an external magnetic field, since current is induced by voltage,
do electrons flow from one side of the rod to another? So is there current even if there's no 'circuit', furthermore does the rod become positively charged in one side and negative in the other?


3. As a motor spins, back emf is induced, to eventually result in NET VOLTAGE of zero
but how is there flow in current if there is no potential difference?
Also is there back EMF in AC motors?

Thanks =]
 
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  • #2
1/ When a conductor and a magnetic field move relative to each other, the charges in the conductor experience a voltage.
It doesn't matter if you move the conductor and keep the magnet still, or if you move the magnet and keep the conductor still. It's the same thing, relative movement produces the voltage.
(You might be interested to know that Einstein was puzzled by this too and it was what made him start thinking about relativity - he was 16. The first part of his famous paper on relativity is about it)

2/ Yes

3/ The same way that if you fill a pipe with water then and a pressure to get it going, then connect the two ends of the pipe together. For a little while at least, the water keeps going even though there's no pressure difference.
And again -yes.
 
  • #3
michojek said:
1. I know if i move a conductor in an external magnetic field, it induces EMF, but
I don't really understand INDEPTH how CHANGE in MFlux induces EMF?
I think something to do with EF and MF...

Look at it this way. If you couldn't see the magnet moving towards you, or you moving towards the magnet, would you be able to tell if you were actually moving towards a magnet or if the flux was just increasing?
 

1. What is EMF?

EMF stands for electromagnetic field, which is a combination of electric and magnetic fields that are produced by the movement of charged particles. It is a form of energy that is present in our everyday environment, including from sources such as power lines, cell phones, and household appliances.

2. What is the difference between electric and magnetic fields?

Electric fields are created by electrically charged particles and can exert a force on other charged particles. Magnetic fields are created by moving electrically charged particles and can exert a force on other moving charged particles. Both types of fields are components of an electromagnetic field.

3. Are EMFs harmful to our health?

There is currently no conclusive evidence that exposure to low levels of EMFs from common sources such as power lines and household appliances is harmful to human health. However, some studies have suggested a possible link between high levels of EMF exposure and certain health effects, such as cancer. More research is needed to fully understand the potential risks.

4. What is the unit of measurement for EMF?

The unit of measurement for EMF is the tesla (T) for magnetic fields and the volt per meter (V/m) for electric fields. However, for everyday purposes, milligauss (mG) is often used as a unit for measuring magnetic fields from common sources.

5. How can I reduce my exposure to EMFs?

To reduce your exposure to EMFs, you can try to limit your use of electronic devices, keep a safe distance from power lines and other sources of high EMF levels, and use shielding materials when possible. It is also important to follow safety guidelines and instructions for using electronic devices and appliances.

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