Oliver Heaviside, George Ashley Campbell, Mihajlo Pupin telecommunication |

## Loading coil

Transmissions over transatlantic telegraph cables
were distorted by an imbalance in the cables
between capacitive and inductive reactance.
Oliver Heaviside determined that transmission
would be free of distortion
when conductance over capacitance was equal
to resistance over inductance,
and suggested balancing the cable
by increasing its inductance
with loading coals.
Meanwhile,
aware of the Heaviside condition
but not of Heaviside’s suggestion
to use loading coils,
George Campbell realized
that he could add loading coils
along the forty-six-mile-long Pittsburgh cable
at every manhole
to improve the clarity of transmissions.
Michael Pupin in the same year
worked on the problem,
but loaded his line with capacitors
rather than inductors. Nevertheless,
he made a legal claim to Heaviside’s idea,
so that today loading coils
are sometimes called *Pupin coils.*

## Heaviside condition

In a transmission line, when the ratio of conductance over capacitance equals the ratio of resistance over inductance, when the ratio of siemens per meter over farads per meter equals the ratio of ohms per meter over henries per meter, then a transmission will not be distorted.

## Lenz’s law

Heinrich Friedrich Lenz explained
that a changing magnetic field in a conductor
induces a magnetic field in the opposite direction
which is why in a circuit an inductor
opposes an alternating current.
This is called *inductive reactance.*

## Intuitive degree

At some point, I assume, if I study and experiment, then the laws of electromagnetism will become intuitive. I’ll see clearly the relations between conductance and resistance, capacitance and inductance, and see how the tiny components work, but now I struggle to comprehend. Until then, I’ll feel deprived, like a person who knows what is beautiful but cannot feel its joy or pain.

An inductor with an inductance of 1 henry produces an electromotive force of 1 volt when the current through the inductor changes at the rate of 1 ampere per second.

See also in

The book of science:Electric conductivity—Humphry Davy, Henry CavendishFaraday’s law of induction—Michael FaradayReadings on wikipedia: