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Current Electricity – A Problem

A student has 2 wires of iron and copper of equal length and diameter. He first joins the two wires in series and passes electric current through the combination which increases gradually. After that he joins the 2 wires in parallel and repeats the process of passing current. Which wire will glow first in each case and why ?

 

Asked Soja

Why is potential difference called an effect and emf is called a cause?

Why is potential difference called an effect and emf is called a cause?

Asked Aadaah Raina

Supercondutors

Superconductors are supposed to be able to carry current flow without loss.  A superconductor loop can generate magnetic fields indefinitely, as long as it remain cool enough to remain superconductors.  So it begs to question — Can we use the magnetic flux generated by the superconductor coil to power a motor compressor to cool the superconductor so that it will remain superconductor forever ?

Asked H.M. Chi

What is displacement current? Why is it necessary?

As you know, the word current means flow. An electric current (conduction current) is caused by flow of electrons.

But while considering the continuity of electric current in a circuit with a capacitor as a component, it becomes difficult to explain the continuity as there is no physical medium between the plates of the capacitor for the electrons to flow. But the effect (magnetic) can be felt in between the plates too. This is explained by the Maxwells equations, the Ampere Maxwell law, also called the modified Ampere’s circuital law.

The original form of Ampere’s circuital law is insufficient to explain the continuity of current in the above case. But according to Maxwell, a time varying electric flux can also produce effects similar to that of conduction current. This “current” (though there is no flow of charges) is termed as displacement current.

Please refer to these links too:

http://en.wikipedia.org/wiki/Displacement_current

http://ocw.mit.edu/courses/physics/8-02-electricity-and-magnetism-spring-2002/video-lectures/8_022002L18.pdf

http://ocw.mit.edu/courses/physics/8-02sc-physics-ii-electricity-and-magnetism-fall-2010/maxwells-equations/the-displacement-current-and-maxwells-equations/

What is the physical meaning of eigen value?

What is the physical meaning of eigen value? What is the physical meaning of magnetic vector potential?

 

Asked Surya

 

Are all theories of Physics based on a mathematics … ?

Are not all theories of physics (general relativity, quantum mechanics and other variations) based on a mathematics of structure? An assumption that the model and its constituents have structure? Structure that assumes space as a necessary, though maybe not formalized component?

English: Quantum black hole Русский: Квантовая...

Could it be that during a black hole collapse that ALL structure is lost? All space is eliminated.  There is no space, only mass/energy?

Posted by Richard

Magnetic Velocity

How would I figure out the velocity of a ball at the end of the chain.
For example if I had 4 half inch magnets each one 6 inches apart with 3 quarter inch steel ball behind each magnet.
If the starting velocity of the first ball to hit the magnet is 10mph.
~~~~~~~~~~~~~~~~~~~~~~~
What if i changed the ball size half way through.
For example if I had 4 half inch magnets each one 6 inches apart with 3 1/4 inch steel ball behind the first two magnets and 3 1/8 inch steel ball behind the last 2 balls
Example video to help understand setup
https://www.youtube.com/watch?v=9LtkIcAIQII

 

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