Are Voltage and Electromotive Force the Same 

Actually if one considers the self inductance of a "long" solenoid winding vs a toroidal winding having an equivalent mean major circumference, wound over identical high permeability core materials of equal diameter and with the same number of turns, the inductances are very close. For instance a 300 turn toroidal inductor wound over a core of major mean radius 5 cm, minor radius 1cm and relative permeability of 200 would have an inductance of around 22.6 mH. A 300 turn solenoidal inductor wound over a core of length 31.4 cm, radius 1cm and relative permeability 200 would have an inductance very close to the toroidal inductance. I would would envisage the toroidal winding simply as a solenoidal winding formed into a closed loop. You are correct that a toroidal inductance can be viewed as a transformer when a secondary winding is added. Toroidal transformers are quite common. The benefit of a well designed toroidal inductor (transformer) is that it has negligible external magnetic field at low frequencies (e.g. an AC mains transformer). The B field is ideally confined within the highly permeable core material. Many people are then at a loss as how to explain induction in a secondary winding with a negligible B field outside the core. While there is a negligible external B field, there is a substantial external vector potential field which is the agent of induction in the secondary winding. James Clerk Maxwell proposed the existence of the magnetic vector potential and its role as the agent of electromagnetic induction. The Aharonov-Bohm experiment is believed to be a modern confirmation of the existence of the vector potential. Early engineers (such as Oliver Heaviside) were unconvinced of the reality of the vector potential, viewing it merely as a useful mathematical construct. In the case of the toroidal transformer the vector potential field is more concentrated within the core window and hence a substantial part of the induction occurs within the core window. But the vector potential (and hence induction) still exists to a lesser extent outside the core window. Bob is incorrect in his belief that the induction is confined to the core window. It occurs to varying degree along any closed path which encloses the core - which of necessity transits the core window once for each secondary turn. If you wish to explore this further there is an excellent paper available on the web entitled "On the fields of a toroid and the role of the vector potential" by Neal Carron. Carron clearly develops the theory of the fields associated with a toroidal winding. Carron does show that with a primary sinusoidal time-varying inductor current there will be a radiated magnetic field external to the toroidal winding - but this radiated near-field field is of insufficient strength to account for any secondary induced EMF.

A coil of uniform resistance forming an unbroken loop will be non-conserative. However, if the loop is broken or the resistance is not uniform, the voltage gradient in the loop is conservative. You are correct on your second question. Try this: take a small DC motor and spin it. See how freely the armature spins. Now short the power connections together and spin it again. Not it stops spinning quickly. That's the motor acting as a generator producing current that tries to turn the motor in the opposite direction.

That's my point. The entity engineers call EMF or voltage differential and physicists call V, is not the same that physicists call emf or Ꜫ. You cannot measure Ꜫ with a voltmeter.

@@Vocademy-Electronics-Tech Thanks again, Bob! Doing my best to get you more subscibers!

@@MrDoneboy Voltage is an informal name for anything measured in Volts. Engineers commonly default to the term voltage, even though physicists have more formalized names. Electric potential is a special case of EMF, when the field is conservative, and the concept of electric potential works in our favor as a shortcut for evaluating the EMF. In general, EMF is the work done by a field, per unit charge, as a charge moves between two points. It is a line integral of E dot dℓ, where E is the electric field, and dℓ is the infinitesimal incremental distance along the path. Given a purely electrostatic field, i.e. a field set up by stationary charges, the closed loop integral E dot dℓ is zero, and the integral E dot dℓ is independent of path. It only depends on the start and end points of the charge's motion. We define electric potential to be this potential function of space, that pre-evaluates this formula as a shortcut for us. We chose a reference point that we define as zero potential, and evaluate this integral to each of the points in space, each starting at that reference point. Usually, the reference point is either ground, or infinitely far away. This is the kind of potential that defines what we normally think of as voltage, and what we use for evaluating Kirchhoff's voltage loop law. Since closed loop integral E dot dℓ is zero, the sum of voltage differences around any loop is also zero, in this special case. When Faraday's law of magnetic induction is also involved, the field is no longer a conservative field. Closed loop integral E dot dℓ, no longer equals zero. Instead, it equals a value that is determined by the rate of change of the magnetic field, and the area it covers. This is what is meant by EMF, when we contrast it from electric potential. It is no longer valid to just evaluate electric potential at the initial point and final point, to determine the work done on the charge. The work done is path-dependent, and so is the voltage induced in the circuit.

Cut the shrooms bro 😂

@@keylanoslokj1806 magic.