Question

is the wire used in this experiment? Show numerically 2) (Note: This question has a long preamble, but not to worry... the question itself is straightforward). In general, the devices we use in our circuits have some internal impedance (resistance is a specific form of impedance). When we use a current meter or function generator in series (as in this experiment) with our circuit elements, we would ideally like these devices to have zero impedance, so they help us obtain measurements without introducing new impedance into the circuit. Similarly, as our voltmeters are in parallel, we would like them to have infinite impedance, for otherwise it will draw some of the current from the rest of the circuit. Of course, there is no such thing as a circuit element as having zero or infinite impedance; this is the circuit equivalent of a frictionless plane or massless rope. So our devices themselves cause systematic errors the impact of which depend on the impedance of other elements in the circuit. However, we can quantify the function generator's internal impedance by treating it as a part of another voltage divider. Indeed, one of the reasons that studying voltage dividers is useful is because they are ubiquitous in circuits, even if it does not appear so at first. This is especially useful when circuits become more complex; if you can reduce part of the circuit to being a voltage divider -even if it has complex combinations of resistors, capacitors inductors, transistors, and so on- -then you can still use the same mathematics established in this experiment. The general voltage divider is as follows: Signal in Signal out Now we can use the flexibility of the voltage divider analysis to determine the internal impedance of the function generator, Rg. The modified version of Figure 1, accounting for the function generator impedance is as follows: