Real concept of flow of Electrons in Conductor
Real concept of flow of Electrons in Conductor
Myself Prof. KALI C.
S. (M.Sc. M. Ed. D.C.S. ) having 45 years of Experience in Physics teaching. It
is observed that there are misconceptions in the students regarding the flow
of Electrons in the Conductor. Do you want to know the real secret of the flow
of Electrons in the Conductor? Then let us see the truth.
Every conductor is made up of atoms. The atom consists of Electron (e-), Proton ( H+ ), Neutron (n0 ). At the center of an atom, there is a nucleus containing protons and neutrons, making the nucleus positively charged. The electrons are revolving in different orbits around the nucleus.orbits round the nucleus.
 Fig A |
Consider sodium metal having Atomic number 11. Its electron distribution is 2,8,1 and hence Valence electron will be 1. Fig A represents electrons distribution in the sodium atom. |
 Fig B |
 Fig C |
To
form a metal large number of atoms are arranged regularly to form a crystal as shown
in Fig B. In the atom, the attractive force on electrons in orbit goes on
decreasing as orbit number goes on increasing. The electron in the last
orbit experiences the least force. When the crystal is formed, the electron in
the last orbit loses control of the nucleus and becomes free. Thus every sodium
atom gets converted to a sodium positive ion and the free electrons are in
random motion in space between localized ions ( Fig C) and (Fig D ).
 Fig D |
Let
us consider one of the electrons at A at any instant. It will follow the random path
due to collision with other electrons. After tine t it may be at B ( Fig D ). Every
electron is in a different random motion. Due to these random motions of
electrons, the
number of electrons crossing across on either side of the cross-section is
equal.
|
Thus there is no current flow in metal even though electrons are
in motion when the battery is not connected.
Effect of application of voltage on metal:-
When
a battery of voltage V is connected, it will supply electric
energy
E
= Ve to every electron of charge e.
Due
to this, each electron gets extra energy to move towards the +ve terminal of the
battery.
As
already the electrons are in random motion now they get extra motion towards
+ve terminal of the battery; i.e., random motion of electron gets superimposed
by motion towards +ve of battery. Here each electron is in random motion along with slight
motion towards the +ve terminal of the battery.
To
understand this more clearly let us see one day-to-day example. On the occasion
of Anant
Chaturdashi, there is a Ganapati procession. In
the procession let us consider Lezim player team is performing
with Lazim.
When these players are performing at one place, all the layers are in
random motion but the entire team is at one place. The procession is not
moving. After some time the team leader forces the team to move forward without
discontinuing the performance. Now players are in random motion along with the forward
motion. But now the procession is in motion. Think electron as player and
the team leader who forces to move as voltage of battery
Fig E |
Every Electron shifts towards the +ve terminal of the
battery along with the random motion. Without voltage, the electron at point A
would have been reached at point B in time duration T ( Fig E ). But on voltage
application, electron reach at point B1 in time duration T. Thus there is a
shift of
BB1
= S in random motion of the electron in
time T.
This is the displacement S in time t and Drift velocity
V
= S / t. |
Now the
number of electrons crossing across on either side of the cross-section is
not equal. Let n be the number of electrons crossing extra
towards +ve terminal of the battery in time t. Total
charge moving towards +ve terminal of the battery will be n.e in time t.
Thus the current I is
the rate of flow charges.
I = ne / t
Current = charge / time
The current is the result of the shifting
of random motion of the electrons towards the +ve terminal of the battery.
The electrons are moving from the -ve terminal to the +ve terminal of the battery
in the circuit. But the conventional current direction is from the +ve terminal
to -ve terminal of the battery in the circuit.
For the animation of electron flow see the Video Source from Youtube
https://www.youtube.com/watch?v=KprFTxjQAoE
Very nicely explained sir.
ReplyDeleteConcept cleared
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Precise and to the point explanation. Simple language. Good work Sir!
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Sir, beautifully explained. Thanks.
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Dr.Suresh Bagi
Physics is a part of our life. It was great learning from u once again. Reminded about my college days. Very informative and nicely explained
ReplyDeleteRespected Sir
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Thanks to all
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