Amplifier (non inverting) question

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In summary, an amplifier has negative feedback applied to it, such that the feedback fraction is 0.5%. If the open loops gain of the amplifier is 10^5, what is the closed loop gain? 199.6.
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peanutbutter
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Homework Statement


An amplifier has negative feedback applied to it such that feedback fraction is 0.5%. If the open loops gain of the amplifier is 10^5 what is the closed loop gain? I get this as 199.6

The amplifier is connected to a signal source of internal resistance 300kohms which provides a sinusoidal signal of 30mV amplitude, when not loaded. If the amplifier has an input resistance of 150kohms and an output resistance of 600ohms what is the amplitude of the voltage signal that would appear at the output terminals of the amplifier when it is
a) open circuit
b) connected to a load resistance of 8 ohms
c) connected to a load resistance of 600 ohms

Homework Equations


Gain of a non inverting amplifier = (R1+R2)/2

Any help would be great. It's multiple choice and the options are parts a,b and c are;

0.003V, 0.03V, 0.3V, 1V, 2V
 
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  • #2
Can anyone help?
 
  • #3

Homework Statement


An amplifier has negative feedback applied to it such that feedback fraction is 0.5%. If the open loops gain of the amplifier is 10^5 what is the closed loop gain? I get this as 199.6

The amplifier is connected to a signal source of internal resistance 300kohms which provides a sinusoidal signal of 30mV amplitude, when not loaded. If the amplifier has an input resistance of 150kohms and an output resistance of 600ohms what is the amplitude of the voltage signal that would appear at the output terminals of the amplifier when it is
a) open circuit
b) connected to a load resistance of 8 ohms
c) connected to a load resistance of 600 ohms

Homework Equations


Gain of a non inverting amplifier = (R1+R2)/R2

Any help would be great. It's multiple choice and the options are parts a,b and c are;

0.003V, 0.03V, 0.3V, 1V, 2V

The Attempt at a Solution


a) open circuit, R1 = 0, R2 = infinity so gain is 1 ==> Vout = 0.03
b) Gain = (600+8)/8 = 76 => Vout is approximately 2
c) Gain = (600+600)/600 = 2 ==> Vout is 0.06 but there isn't an option for this. :S
Attempt
a) open circuit, R1 = 0, R2 = infinity so gain is 1 ==> Vout = 0.03
b) Gain = (600+8)/8 = 76 => Vout is approximately 2
c) Gain = (600+600)/600 = 2 ==> Vout is 0.06 but there isn't an option for this. :S

Could someone help?
I've shown my working.
 

1. What is a non-inverting amplifier?

A non-inverting amplifier is an electronic circuit that amplifies an input signal while maintaining the same polarity. This means that the output signal is in phase with the input signal.

2. How does a non-inverting amplifier work?

A non-inverting amplifier uses a feedback loop to amplify the input signal. The input signal is fed into the non-inverting input of an operational amplifier, and the output is fed back to the inverting input. This creates a closed loop that amplifies the input signal.

3. What are the advantages of a non-inverting amplifier?

Non-inverting amplifiers have a high input impedance, meaning that they do not draw much current from the input signal. They also have a low output impedance, providing a strong and stable output signal. Additionally, non-inverting amplifiers have a high gain and low distortion, making them useful for amplifying weak signals.

4. How do you calculate the gain of a non-inverting amplifier?

The gain of a non-inverting amplifier is calculated by dividing the feedback resistor value by the input resistor value. The formula for gain is (1+ Rf/Rin), where Rf is the feedback resistor and Rin is the input resistor.

5. What applications are non-inverting amplifiers commonly used for?

Non-inverting amplifiers are commonly used in audio equipment, signal conditioning, and instrumentation. They are also useful for buffering and amplifying sensor signals in electronic circuits.

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