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# Tag Archives: electromagnetism

## Nature of Electromagnetic Waves

When we represent the frequency, amplitude, and wavelength of any electromagnetic radiation on a graph we see a wave like in water. Is this just a geometric representation or do the “packet” aspects of these waves actually move physically like the mathematical representation.

Hope that the following videos explain the concept better English: Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This diagram shows a plane linearly polarized wave propagating from left to right. The electric field is in a vertical plane and the magnetic field in a horizontal plane. http://weelookang.blogspot.com/2011/10/ejs-open-source-propagation-of.html (Photo credit: Wikipedia) ## Magnetic field due to current A spinning electron creates a magnetic field.But what about an electron inside a current carrying wire electron is spinning around its axis and revolving in loop,both simultaneously.So,what if both the situations contradict (both magnetic fields are in opposite direction ).net M.F. should be zero then. I mean what is the fate of electron in a current carrying wire with respect to its spin? ## Neutrons, Neutrons, Neutrons

I understand that  in large elements which contain many protons, there exist too many neutrons to extend the strength of strong nuclear force and to overcome the electromagnetic repulsion force of protons. Such elements are stable in this way. But, I read that element with too many neutrons are also unstable. WHY ?  What I know is that too many neutrons can’t enlarge the electromagnetic repulsion force and can increase the strong nuclear force, so they even make the nucleus more stable . What’s wrong with me ? Please!  ## Continuity of Magnetic Field Lines

I was taught in school that magnetic lines can not cross each other without breaking. Also i was taught that magnetic field lines are unidirectional traveling out of the north end of the magnetic field and connecting to the south magnetic pole. My question is, In the event of the lines being broken, would the broken or open north magnetic lines coming out of the north pole of the magnetic field( traveling at the speed of 186,000 miles per second, the speed of light) be able to connect with any other south magnetic poles they encounter even a second or more away.thank you, Ron G.  ## Why there is no magnetic field around a disconnected copper wire

Moving electrons produce magnetic field right? Electrons on earth are moving at an average of 27.83m/s due to earths rotation plus 30m/s due to earths revolution and may be more due to sun’s revolution and our galaxy’s revolution.
since there is no absolute motion, how can we tell if electrons are moving?
If the electrons are moving, anyway, why is there no magnetic field around a disconnected copper wire? Right hand rule is a physics principle applied to electric current passing through a straight wire, resulting in a magnetic field. The thumb points in the direction of the conventional current (from positive to negative), and the fingers in the direction of the magnetic field. (Photo credit: Wikipedia) ## Why there are Sine functions in Physics?

Why are sine functions used in some of the equations in physics?
For example,in the expression for instantaneous emf induced in a rotating conductor placed in an uniform magnetic field which is given by
E=B*L*V*sin(theta)
where,
B is the strength of the magnetic field,L is the length of the conductor and (theta) is the angle between the direction of motion of the conductor and the magnetic field,and here,my question is why do we use sine function in this expression?what is its need? The function sin (theta) in a right angled triangle = opp. side /Hypotenuse

When we have to take a component perpendicular to another, we take the sine function. ## Why is the force on a wire NOT carrying current is zero when kept in a magnetic field?

Explain zero force acting on a wire  which is not carrying current,on being placed inside a magnetic field. A charge at rest will not experience any force in a magnetic field, but a moving charge will experience  a force unless it is moving parallel to the field.

In a conductor, the electrons are in rapid and random motion, but the conductor will not experience a force until a current is passing through it. (Even though the electrons are not at rest). This is because, in the absence of a current, the motion of electrons is random and there is no net drift of electrons in any direction. Thus the forces cancel out.

When a current is passed through the wire, there is a net drift and hence a net force is experienced by the current carrying conductor in a magnetic field.

Further, I want to mention that the force is experienced between the existing field and the field produced by the moving charges/ current. ### Hits so far @ AskPhysics

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