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Water flows from mountain top to valley
down. All fluids flow from high pressure
to low pressure. Heat flows from high
temperature to low temperature.
Similarly, the electrons flow from surplus point to starving point. In chemical reactions of a battery, there are
more electrons at negative electrode and there is lack of electrons at positive
electrode. Then the electrons try to
flow from negative to positive electrode.
When we connect negative and positive point by a wire, the current
(electrons) flow from high electric potential to low electric potential. (Note: Electrons flow from negative to positive
end and the conventional current is taken to flow from positive to negative).
Resistance: We know the current flows through the metal
wire. The atoms in the metal are never
at rest. They vibrate due to
temperature. The electrons that move
through these vibrating atoms get hits.
So the metal atoms offer “resistance” to the current.
So the ohm’s
law says,
"Electric
current = potential difference between ends/ resistance".It means the
electric current increases as the voltage (potential difference)
increases. But it decreases as the
resistance increases.
If we cool down the conductor (wire), the
atomic vibrations slow down. At a
particular temperature the atoms may comes to stand still. Then the electrons can fly through the wire
without hindrance. Now the resistance of
the conductor is almost zero. This conductor
is called superconductor. Now, what are
the consequences?
Current =
Voltage/ resistance = V/0= infinity.
That means,
once the current is setup in the superconductor it will go on for a very long
time. There will be no loss of
energy. In ordinary conductor, the
electrons collide with atoms and loss energy in the form of heat and sound. Superconductor is now possible at very low
temperature. But, still elusive at
normal temperature. Once we have superconductor
in room temperature, the electrical energy can be distributed without much
loss, appliances can work with less waste.
We can make super magnet which can levitate a train and move us fast and
many more.
May the
research in superconductivity be successful.
