In order to prove that apparent change in d(fi)/dt does not produce

In order to prove that apparent change in d(fi)/dt does not produce
emf in the circuit, we have to design a circuit in such a way that the
whole circuit or a part of it moves in the magnetic field without
change in the flux linking with it. However hard you may try, whatever
contraption you may design, this is impossible to achieve. This is
possible only when the circuit itself is destroyed. Barnett did it.
Another classic example is Faraday's disc in which there is no formal
circuit to account for d(fi)/dt. In spite of this obvious fact, the
concept of flux linkage is introduced in a tortured and wrong way.
A |
* |
* |
* ----------------------
C*******B | |
fig1 | fig2 |

Consider a conducting disc, rotating anticlockwise around
the center C. (Fig.1, draw a circle with CB as radius and c as a
center). Voltage generated is measured between the brush B at the rim
and another at axle. Magnetic flux is uniform and normal to the disc.
Argument goes as follows,
Since the position of the brush B is fixed, the radius CB
is fixed. Consider any arbitrary radius CA, which is rotating along
with the disc. ACB forms an imaginary circuit, area of which is
continuously increasing for one rotation. (Even this description is
not properly explained. What happens when CA takes one complete round
and coincides with CB? Maximum flux suddenly becomes zero. To avoid
this contradiction, we must take in to consideration two areas. One
formed by the short arc and the other formed by the remaining arc. One
area in increasing and the other decreasing, both producing
electromotance in CA in the same direction. Now there is no sudden
change any time).
First we had imaginary change in flux linkage and now we
have an imaginary circuit! Anyway this contrived explanation can
easily be destroyed by making a simple modification. Just bend the rim
so that it forms a circular flange as shown in fig.2. (Fig1 is a plan
and fig2 an elevation). Replace the brush B by a hollow cone, on the
end circle of which the flange of the disc rests. Thus every point of
the rim now makes a contact and current never flows along the rim.
Apex of the cone at bottom serves as a terminal. Now there is no fixed
radius and no circuit can be formed on the disc.
In fact we never had any circuit on the disc. What we have
is an assembly of charges rotating in the magnetic field and
experiencing a force on account of the property 5 of article 17.
Another example is that of an electron rotating on the
periphery of the cylindrical magnetic flux. There is no circuit for a
single electron. Flux on all sides of it remains unchanged. It
experiences a force not due to change in flux linkage. It is due to
property 5.

Can we have an apparent change in the flux linkage without
any part of the circuit actually cutting the flux? Yes we can, in the
following expt. described in the book, Principles of electricity and
magnetism by E.M.Pugh and E.W.Pugh,
------------------B
/
--- / ---
| | A \ | |
----- \ ----
\------------------ C


Consider a toroidal core with round cross section,
carrying constant magnetic flux. Two conducting spring strips B and C
touch each other at point A in the window of a toroid. Galvanometer is
connected between B and C. These strips are fixed on an insulating
rod. When this rod is pulled out, each point of B and C, touching at
A, slide over the core. This portion of the core is bare and you can
cover it by a copper ring, for easy sliding and better electrical
contact. It can be observed that the circuit ABC is never electrically
broken during this operation. In this expt, no part of the circuit
actually moves through the magnetic flux and yet the flux linking with
the circuit changes from maximum to zero.
However emf generated is zero because apparent change in
the magnetic flux cannot generate emf.
Thus force is exerted on the charge only when the flux is
'actually' changing in the magnitude or when there is relative motion
between the two.
=============================================================================
This is one article out of a serial. New visitors should go through
all the previous. Dates are posting dates. Articles are posted to 1.
Alt.sci.physics.new-theories 2.Sci.physics 3.sci.physics.electromag
4. sci.physics.relativity


1. Limitation of Divergence theorem 8-3-04 1,2,3,4
2. Electron positron annihilation 12-3-04 1,2,3,4
3. Changing magnetic field does
not produce electric field 17-3-04 1,2,3,4
4. Barnett's experiment 22-3-04 1,2,3,4
5. Relativity and electrodynamics 25-3-04 1,2,3,4
6. Relativity of two moving charges 2-4-04 1,2,3,4
7. Relativity of steady charge and current 11-4-04 1,2,3,4
8 Relativity of two currents 14-4-04 1,2,3,4
9. Nature of electric field 16-4-04 1,2,3,4
10. Magnetic field is real 22-4-04 2,3,4
11. once more relativity 5-5-04 1,2,3,4
12. A new paradox in SR 10-5-04 1,2,3,4
13. Ampere's law proves reality of magnetic field 17-5-04 1,2,3,4
14 Magnetic field acts at a distance 21-5-04 1,2,3,4
15. Magnetic field energy 25-5-04 1,2,3,4
16. Current without magnetic field 30-5-04 1,2,3,4
17. Properties of the magnetic field 5-6-04 1,2,3,4
18. Magnetic field never produces electric force 8-6-04 1,2

In order to prove that apparent change in d(fi)/dt does not produce
emf in the circuit, we have to design a circuit in such a way that the
whole circuit or a part of it moves in the magnetic field without
change in the flux linking with it. However hard you may try, whatever
contraption you may design, this is impossible to achieve. This is
possible only when the circuit itself is destroyed. Barnett did it.
Another classic example is Faraday's disc in which there is no formal
circuit to account for d(fi)/dt. In spite of this obvious fact, the
concept of flux linkage is introduced in a tortured and wrong way.
A |
* |
* |
* ----------------------
C*******B | |
fig1 | fig2 |

Consider a conducting disc, rotating anticlockwise around
the center C. (Fig.1, draw a circle with CB as radius and c as a
center). Voltage generated is measured between the brush B at the rim
and another at axle. Magnetic flux is uniform and normal to the disc.
Argument goes as follows,
Since the position of the brush B is fixed, the radius CB
is fixed. Consider any arbitrary radius CA, which is rotating along
with the disc. ACB forms an imaginary circuit, area of which is
continuously increasing for one rotation. (Even this description is
not properly explained. What happens when CA takes one complete round
and coincides with CB? Maximum flux suddenly becomes zero. To avoid
this contradiction, we must take in to consideration two areas. One
formed by the short arc and the other formed by the remaining arc. One
area in increasing and the other decreasing, both producing
electromotance in CA in the same direction. Now there is no sudden
change any time).
First we had imaginary change in flux linkage and now we
have an imaginary circuit! Anyway this contrived explanation can
easily be destroyed by making a simple modification. Just bend the rim
so that it forms a circular flange as shown in fig.2. (Fig1 is a plan
and fig2 an elevation). Replace the brush B by a hollow cone, on the
end circle of which the flange of the disc rests. Thus every point of
the rim now makes a contact and current never flows along the rim.
Apex of the cone at bottom serves as a terminal. Now there is no fixed
radius and no circuit can be formed on the disc.
In fact we never had any circuit on the disc. What we have
is an assembly of charges rotating in the magnetic field and
experiencing a force on account of the property 5 of article 17.
Another example is that of an electron rotating on the
periphery of the cylindrical magnetic flux. There is no circuit for a
single electron. Flux on all sides of it remains unchanged. It
experiences a force not due to change in flux linkage. It is due to
property 5.

Can we have an apparent change in the flux linkage without
any part of the circuit actually cutting the flux? Yes we can, in the
following expt. described in the book, Principles of electricity and
magnetism by E.M.Pugh and E.W.Pugh,
------------------B
/
--- / ---
| | A \ | |
----- \ ----
\------------------ C


Consider a toroidal core with round cross section,
carrying constant magnetic flux. Two conducting spring strips B and C
touch each other at point A in the window of a toroid. Galvanometer is
connected between B and C. These strips are fixed on an insulating
rod. When this rod is pulled out, each point of B and C, touching at
A, slide over the core. This portion of the core is bare and you can
cover it by a copper ring, for easy sliding and better electrical
contact. It can be observed that the circuit ABC is never electrically
broken during this operation. In this expt, no part of the circuit
actually moves through the magnetic flux and yet the flux linking with
the circuit changes from maximum to zero.
However emf generated is zero because apparent change in
the magnetic flux cannot generate emf.
Thus force is exerted on the charge only when the flux is
'actually' changing in the magnitude or when there is relative motion
between the two.
=============================================================================
This is one article out of a serial. New visitors should go through
all the previous. Dates are posting dates. Articles are posted to 1.
Alt.sci.physics.new-theories 2.Sci.physics 3.sci.physics.electromag
4. sci.physics.relativity


1. Limitation of Divergence theorem 8-3-04 1,2,3,4
2. Electron positron annihilation 12-3-04 1,2,3,4
3. Changing magnetic field does
not produce electric field 17-3-04 1,2,3,4
4. Barnett's experiment 22-3-04 1,2,3,4
5. Relativity and electrodynamics 25-3-04 1,2,3,4
6. Relativity of two moving charges 2-4-04 1,2,3,4
7. Relativity of steady charge and current 11-4-04 1,2,3,4
8 Relativity of two currents 14-4-04 1,2,3,4
9. Nature of electric field 16-4-04 1,2,3,4
10. Magnetic field is real 22-4-04 2,3,4
11. once more relativity 5-5-04 1,2,3,4
12. A new paradox in SR 10-5-04 1,2,3,4
13. Ampere's law proves reality of magnetic field 17-5-04 1,2,3,4
14 Magnetic field acts at a distance 21-5-04 1,2,3,4
15. Magnetic field energy 25-5-04 1,2,3,4
16. Current without magnetic field 30-5-04 1,2,3,4
17. Properties of the magnetic field 5-6-04 1,2,3,4
18. Magnetic field never produces electric force 8-6-04 1,2