00:01
Now we are talking about an amplifier circuit for the example.
00:06
In an amplifier circuit, we means we have some resistive component, we have some inductive component, we have some capacitive components.
00:19
And we know the reactance of a inductor is depending upon its means frequency.
00:31
Is 2 pi fl and the reactance of a capacitor is equal to 1 upon 2 pi fc and so we can say that the reactance of inductor and capacitor vary with their their frequency it means if we if we design any electronic amplifier circuit then its performance, its output will vary based upon the frequency of the input signal, right? because at different frequency, the behavior of inductor and capacitor will change.
01:27
So the performance of the whole circuit, which has inductor and capacitor inside will also change.
01:34
So this is why the gain of the amplifier, now what is gain? gain of the amplifier is equal to the output voltage of amplifier v2 upon input voltage of amplifier v1.
01:56
And we also define the gain of the amplifier in terms of power as output power upon input power.
02:07
P2 is the output power, input, and p1 is input power.
02:14
Now it means the gain of that because since the p1, p2 is supposed p1 is fixed, p1 is the input voltage.
02:30
Now input voltage is say, say example, 100 volt 50 hertz.
02:38
Now why we are talking about specifically about amplifier because amplifier amplifies music or any audio signal an audio signal has the component of different frequencies and based for those different frequencies the l and c will behave differently because their reactants vary with the frequency this is the basic idea it means the output of an amplifier will depend upon its frequency.
03:15
And the input of an amplifier is not a fixed frequency.
03:20
Like suppose we connect an amplifier with some ac signal source and the ac signal source gives a fixed input 100 volt 50 hertz.
03:31
Then the value of the capacity and in, inductive reactions will be fixed because f is fixed.
03:40
But if we connect the amplifier to a source of audio music or any audio voice, then there are so many instruments, means are playing and also the frequency of a single person who means who is recording the audio changes, right? it speeds changes.
04:01
So based on all those things, we can say in case of an amplification, the input has always variable frequency.
04:13
It means the gain of the amplifier will be variable, always variable.
04:20
Why input is always variable? it has many instruments, many tones, many notes of different frequencies.
04:29
So if this is the basic idea, why the gain of the amplifier varies with frequency? why gain? gain varies because gain is output upon input the output will will vary based on the frequencies because output will depend upon the in favor of inductor and capacitor and at their behavior vary with the frequency so output also vary with the frequency so gain also vary with the frequency so if we plot a graph between the gain and the frequency of the frequency of of amplifier, the means graph is somehow somewhere like this.
05:17
What does it explain? it explains that there are some means frequency range where the gain is fixed.
05:32
Gain does not vary.
05:35
These are two means frequency ranges.
05:39
We can call them f1 and f2.
05:44
Right if we operate the amplifier in this frequency range its gain will remain constant it will not vary and we actually does not want want gain to vary because if gain will vary then the sound won't be equalized the output won't be equalized so if we operate here it's fine it's fine but the main problem here is the the problem is that if we operate the means amplifier only in this frequency range it will not amplify all the frequency component present in the input because any instrument or any type of voice may fall here may fall in this may fall just below f1 or just after f2.
06:40
So it will not amplify...
