since in an op amp the input resistance is very very high
so at the input node no current flows in to he opamp
and ,it passes through feed back resistance, so at the
input we assume virtual ground
input resistance of the opamp is very high, so current is
cannot be flow through opamp and it passes through feedback
path. it create ground at input but it is not a actual
ground so we assume that it is virtual ground.
Since the resistance between inverting and non inverting
terminlas of op amplifier is very high. Therefore ideally
no current or very samll current can flow through these
termonals. if we model this we must have
I+ = 0 = I-
So this creats a ground which is not like the actual ground
but it is said to be the virtual ground.
opamp gain is is very high about greater than 1000
so according to formula gain A=Vo/Vi, Vo=A*Vi, Vo=1000*Vi,
so if we apply small voltage of .025V, we get o/p volatage
Vo=1000*.025=25V, so due to high gain we need very small
or negligible amount of i/p voltage or current. so we
ground the one port at i/p side it means no current flows
through it but practically it always has some value in the
fraction of ampere.
In an opamp the input impedance is very high because of the
first stage which is dual input balanced output differential
amplifier. Due to this, negligible current flows into the
opamp. This suggests that the potential difference across
the input impedance is zero and if any one terminal is
grounded then the potential at the other end is zero.
However it is called virtual ground as ordinary ground has
zero potential but can sink infinite current whereas virtual
ground has zero potential and can sink zero current.
since there are two input terminals in the inputside so the
resistance between the two input terminal is very very
high.so a negligible amount of current flows through op-amp
otherwise the current will be zero,then current only passes
through feedback resistance.hence the input terminal is
assumed to be virtual ground
we know that open loop gain of an ideal op-amp is
infinity.This implies that the differential voltage is
zero.That is, voltage at the inverting terminal=voltage at
the non inverting terminal.If the non inverting terminal is
grounded ,it means that the inverting terminal is
grounded.In other words there is a virtual short cicuit
between the two terminals.,but no current flows through it
since there is no physical connection between the two.This
is virtual ground in op amp.
input resistance of the opamp is very high, so current is
cannot be flow through opamp and it passes through feedback
path. it create ground at input but it is not a actual
ground so we assume that it is virtual ground.
A man whose age is 45 yrs has 3 sons named John,jill,jack.
He went to a park weekly twice.he loves his sons very much.
On a certain day he find # shopkippers sailing different
things. An apple cost 1penny, 2chocalate costs 1penny.& 3
bananas cost 1 penny. He has bought equal no. of apple,
chocolate & banana for each son. If the total amount he
invest is 7 penny then how many he has bought from each
piece for his son?
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