Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

Perpendicular electric and magnetic field creates light or other electromagnetic waves. Is it a necessary property to have a perpendicular fields? If not what would happen when the fields are not perpendicular?

share|improve this question
1  
A moving electric field, creates the perpendicular magnetic field. –  Optionparty Apr 14 '13 at 19:36
2  
@KaziarafatAhmed: Yes there is! In wave guides there modes of propagation. What we know as transverse electromagnetic field is just the TEM mode of a field. There are also the TE(transverse electric mode) with $B_z\neq 0$ and the TM(transverse Magnetic mode) with $E_Z\neq 0$ where $z$ is the direction of propagation! –  Thanos Apr 18 '13 at 12:33
3  
Just put a charge at rest in a magnetic field. The Coulomb field goes out in all directions, and will cross the magnetic field at every possible angle. Nothing special happens. –  Michael Brown Apr 18 '13 at 12:44
1  
please note that if $\vec{E} \vec{B}$ is not equal to $0$, i.e. fields are not perpendicular, then there always exist a reference frame where $\vec{E}$ is parallel to $\vec{B}$. In particular, this is the case of neutrino field. –  Murod Abdukhakimov Apr 18 '13 at 14:54
1  
@MurodAbdukhakimov: if ... fields are not perpendicular, then there always exist a reference frame where E is parallel to B Not true. The quantity $E\cdot B$ is a relativistic invariant. See en.wikipedia.org/wiki/… –  Ben Crowell Aug 17 '13 at 18:29

3 Answers 3

Yes there is! In wave guides there modes of propagation. What we know as transverse electromagnetic field is just the $TEM$ mode of a field. There are also the $TE$(transverse electric mode) with $B_z≠0$ and the $TM$(transverse Magnetic mode) with $E_z≠0$ where $z$ is the direction of propagation!

share|improve this answer

Electricity can be static, like the energy that can make your hair stand on end. Magnetism can also be static, as it is in a refrigerator magnet. A changing magnetic field will induce a changing electric field and vice-versa—the two are linked. These changing fields form electromagnetic waves. Electromagnetic waves are formed by the vibrations of electric and magnetic fields. These fields are perpendicular to one another in the direction the wave is travelling. Once formed, this energy travels at the speed of light until further interaction with matter.

Maxwell developed a scientific theory to explain electromagnetic waves. He noticed that electrical fields and magnetic fields can couple together to form electromagnetic waves. The terms light, electromagnetic waves, and radiation all refer to the same physical phenomenon: electromagnetic energy. This energy can be described by frequency, wavelength, or energy. All three are related mathematically such that if you know one, you can calculate the other two. There’s a particle model and a wave model for electromagnetic radiation, and as we know electromagnetic radiation have dual nature. For an electromagnetic radiation to persist the two electric and magnetic fields have to propagate in a perpendicular direction to each other, EM waves consist of oscillating electric and magnetic fields.

share|improve this answer
1  
This doesn't really address the question of whether or not E and B fields can be non-perpendicular. It only states that the fields can only be perpendicular for EM radiation, which is misleading because there are situations in which you can have E and B fields that are not perpendicular –  Jim Sep 15 at 18:09
    
I don't think you read my question carefully. @hariom –  Arafat Sep 15 at 18:17

According to my understanding at physics, an electric field which is static cannot create any magnetic field.According to faraday for a magnetic field to exist there should be a varying electric filed(which varies over time).A simple example is battery connected to coil which is moved in and out near the galvanometer shows deflection(A galvanometer is device which detects magnetic filed by coupling magnetic filed near its vicinity to the coil inside and it internally has magnet which orients along the direction of earths's.The needle which is connected the coil coupling the magnetic field experiences a torque due to the EMF induced in it,and rests in the direction such that the earths magnetic field and the coupled magnetic are perpendicular to each other..hence the deflection of the galvanometer needle shows the stregth of magnetic field.

share|improve this answer
1  
According to faraday for a magnetic field to exist there should be a varying electric filed(which varies over time). No. This is only one of the two source terms for magnetic fields in Maxwell's equations. –  Ben Crowell Aug 17 '13 at 18:31

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.