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Why power does not amplify?

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kohtwe

Junior Member level 2
Why don't power amplify

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Re: Why don't power amplify

what means :?: :?: :?:

Re: Why don't power amplify

kohtwe said:
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i couldn't understand the question posted by you..plz redefine it so that we will be able to answer it...

Re: Why don't power amplify

Hi Everybody,

I think kohtwe mean "Why amplifier didn't amplify power?"

In general, the purpose of an amplifier is to take an input signal and make it stronger.
Amplifier can amplify powre.
Plz any comment ???????????????

:?:
ZAW

Why don't power amplify

Current or Voltage are amplify. Why don't power amlify?

Re: Why don't power amplify

kohtwe,
Power gain equals output power divided by input power. For example: An amplifier has a 1000 Ohm input resistance, a voltage gain of 10, and an output load of 100 Ohms.
~
Assuming the amplifier is operated in its linear region, the following relationships hold:
~
Input power = Vin^2/1000
Output power = Vout^2/100 = (Vin X 10)^2/100
Power gain = [(Vin X 10)^2 / 100] / [Vin^2/1000]
~ = 1000.
~
The power is amplified by a factor of 1000.
Regards,
Kral

Re: Why don't power amplify

in my opinion (i m not sure), when u amplify voltage, u r amplifing power (the context seems wrong anyway),,
power=VI (i m not considering time)
b/c u r amplifying ur voltage by consuming ur battery power, amplifier don't sinks the source of signal for amplification..
...........
if i m wrong, kindly let meknow...

Re: Why don't power amplify

Naveed Alam,
Consider the following example:
An amplifier has an input resistance of 10K Ohms, a gain of 2, and a load resistance of 100K Ohms.
~
With a 1 Volt input, the output voltage is 2 Volts
~ The input power = (1^2)/10000 = .0001W = .1 mW
~ The output power = (2^2)/100000 = 4/100,000 = .00004W = .04 mW
~ The power gain = .04/.1 = .4 => -3.9794dB.
Regards,
Kral

Why don't power amplify

As far as I know ,the basic operation of a power amplifier is to amplify both current as well as voltage.So if we want to find the power gain,it is current gain into voltage gain.

Re: Why don't power amplify

neils_arm_strong,
Power gain = (Output Power) / (Input Power). In some cases, power gain is not a useful parameter. For example, if an amplifier has infinite input impedance, and a finite load, the input power would be zero, and the power gain would be infinite, but this does not have any practical significance. However, in many RF applications, you are working with a specific characteristic impedance, e.g., 50 Ohms. In these applications, both input power and output power have significance.
regards,
Kral

Re: Why don't power amplify

hi Kral..
so, it means that power amplification exists..interesting for me!!!!

some one said here that amplification means that current and voltage both amplifies.. this is not essential..there are amplifiers which amplifies both, but some amplifies only voltage..for reference read , COMMON-BASE, COMMON, EMITTER, AND COMMON BASE amplifiers.....
Regards

Re: Why don't power amplify

in case of power amplifiers,we are always concerned about its efficency and least bothered about gain..why it isonly a stepmother treatment for gain ..i couldn't understand...

Re: Why don't power amplify

There is no power amplification in the truest sense. Law of conservation of energy implies that no new energy can be generated. So the power amplification we are talking is only AC power amplification. An AC signal can be voltage, current or power amplified. The power required for this power amplification comes from the DC battery supply.
Here comes the concept of efficiency, which determines how much of the battery power is actually used for AC signal amplification and how much is dissipated in the devices.

Why don't power amplify

Hi....

I also think as lavitaebelle !! ! !
To amplify a thing (eg:voltage or current),we will lost other one thing.
But this is only my suggestion.

Any comment are welcome!!

Re: Why don't power amplify

zawminoo said:
To amplify a thing (eg:voltage or current),we will lost other one thing.
But this is only my suggestion.
NO, this is property of transformer..amplifiers do amplification at the cost of Battery..so, no need to reduce the other one..

Regards

Re: Why don't power amplify

Like someone already said, amplifiers run off power. The power delivered to the signal / power used from the source is the efficiency. No new "power" is created, Only used.

Why don't power amplify

Power can be amplified. This is where the concept of power amplifiers comes into picture.

If you amplify voltage definitely the output power defined by Pout=Vout*Iout will be more than Pin=Vin*Iin. And so you have amplified power.

Re: Why don't power amplify

soniya_ahuja said:
Power can be amplified. This is where the concept of power amplifiers comes into picture.

If you amplify voltage definitely the output power defined by Pout=Vout*Iout will be more than Pin=Vin*Iin. And so you have amplified power.

...there exists a lot of difference between Voltage amplifier and power amplifier...both cannot be equated at any time

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