why resistance to a voltage source is connected in series

Question

anonymous · Answer

The resistance represents the internal resistor and has in most cases a small value. This is the best representation because the next stage has an input voltage. You want to konow ho much signal is lossed across the resistance Example A voltage buffer amplifier is used to transfer a voltage from a first circuit, having a high output impedance level, to a second circuit with a low input impedance level. The interposed buffer amplifier prevents the second circuit from loading the first circuit unacceptably and interfering with its desired operation. In the ideal voltage buffer in the diagram, the input resistance is infinite, the output resistance zero (impedance of an ideal voltage source is zero). Other properties of the ideal buffer are: perfect linearity, regardless of signal amplitudes; and instant output response, regardless of the speed of the input signal. Read more: http://www.answers.com/topic/buffer-amplifier#ixzz1jeoQzdS2