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Laboratory work #40
THE DETERMINATION THE ELECTROMOTIVE FORCE BY
THE COMPENSATION METHOD

Aim of work: the determination of EMF by the compensation
method.
Device and accessories: standard and research batteries,

slidewire, resistance box, galvanometer.

1. The Direct Current Conditions of Existence. The Field of
Outside Forces. Electromotive Force

Direct electric current can exist only when the electric field
inside a conductor is not zero.

1. The electric current magnitude is the same for all conductor
cross-areas.
2. The direct current is always closed because charges must be
returned.

3. The closed direct current cannot exist only due to Coulomb
forces because they cannot transfer positive charges from the lower
potential to the larger one, namely against electric field E. Therefore,

there necessarily must non-coulomb outside forces exist.
Outside forces are non-electrostatic forces, the action of which
on electrons in conductors, cause their directed movement and support

the direct electric current in a circuit. The outside forces (in opposite
to Coulomb forces) do not join unlike charges but separate them and
support the potential difference at the conductor ends. Fig.1.1 shows
an example of how a pump creates "outside forces".

Figure 1.1

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