Understanding the Difference Between B and E Fields

In summary, the term "magnetic induction" is used for B instead of "magnetic field strength" due to the split between physicists and engineers in the 1950s. Engineers were more interested in magnetic flux and invented the unit "Weber" for flux and "magnetic induction" for B. However, this term is not descriptive and can cause confusion with E, the electrical counterpart. Physicists recognize that E and B are components of the same tensor and use the unit "gauss" for both. On a smaller scale, there is a difference between B and H, just like there is between E and D. While B depends on the medium, H does not.
  • #1
manjuvenamma
102
0
Why don't we call B magnetic field strength like we call E, the electrical counterpart. In stead we call it magnetic induction which is less descriptive.
 
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  • #2
That is due to the intenational conferences the "named" physical quantities and invented SI. Unfortunately, there was a split in the '50s between physicists and (mostly industrial) engineers. The engineers were most interested in magnetic flux, which powered their generators. They invented the Weber of flux and called B "magnetic flux density" in units of Weber per square meter. That name was unwieldy, even for them, so someone suggested the strange term "magnetic induction". The engineers were careful not to give B the same name as E, so as not to confuse the two. Physicists know it is no confusion, after Maxwell and Einstein, that E and B are just different components of the same tensor. Several advancedl EM texts call B the magnetic field as you and I suggest.
These books also use the same unit, gauss, for B and E, in gaussian units.
 
  • #3
The problem is that, as soon as you look at material properties, B is not a good descriptor of magnetic field strength, which is better described by H.
 
  • #4
manjuvenamma said:
Why don't we call B magnetic field strength like we call E, the electrical counterpart. In stead we call it magnetic induction which is less descriptive.

I'm not sure what you mean by "counterpart"? "E" has units of volts/meter, and is the electric field intensity. "H" has units of amps/meter and is called magnetic field intensity. It appears that E and H are "counterparts". Also, at a boundary of 2 different materials, the "normal" (perpendicular) components of "B" in both materials, and that of "D" in both are equal. But, the tangential components of "E" are equal for both materials, as well as that of "H".

It is obvious that "B" is the counterpart of "D", the electric flux density, aka "electric displacement", whereas "H" is the counterpart of "E".

I hope this helps. BR.
 
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  • #5
see B is magnetic induction which gives effect of magnetic field H .they both look like same macroscopicaly but on a smaller scale there is a huge diff. b/w them just like there is b/w E and D.
B will also depend on the medium while H does not.
 

1. What is the difference between B and E fields?

The B and E fields, also known as the magnetic and electric fields respectively, are two components of the electromagnetic field. The main difference between them is their direction of force. The B field is a vector field that exerts a force on charged particles in a perpendicular direction to their velocity, while the E field exerts a force on charged particles in the same direction as their velocity.

2. How are B and E fields created?

B and E fields are created by electric charges and magnetic dipoles, which are sources of electric and magnetic fields respectively. These fields can also be created by changing electric and magnetic fields, such as in electromagnetic waves.

3. What are some common applications of B and E fields?

B and E fields have various applications in modern technology. The E field is used in devices such as capacitors and antennas, while the B field is used in MRI machines, electric motors, and generators.

4. What are the units of measurement for B and E fields?

The units of measurement for B and E fields are different. The B field is measured in teslas (T) or gauss (G), while the E field is measured in volts per meter (V/m).

5. How do B and E fields interact with each other?

B and E fields can interact with each other in a phenomenon known as electromagnetic induction. When a changing magnetic field passes through a conducting loop, it creates an induced electric field, and vice versa. This is the principle behind generators and transformers.

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