Reactance X a part which varies with frequency due to capacitance and inductance. The alternating current lags or leads the voltage depends upon the nature of reactance component of impedance whether predominantly inductive or capacitance. The inductance and capacitance causes phase shift between current and voltage, which means the resistance and reactance cannot be simply summed up to give impedance. Instead, they must be summed up as vectors with reactance at right angles to resistance, as shown in the figure below.
Image will be uploaded soon. There are four electrical quantities which determine the impedance Z of a circuit: These are: resistance R , capacitance C , inductance L and frequency f. The measure of opposition of inductance and capacitance to current is known as reactance, denoted by X.
It varies with the frequency of electrical signals and is measured in ohms. Reactance is of two types:. Capacitive reactance X c , and. Inductive reactance X L. The total reactance X is equal to the difference between the two:. The capacitive reactance is a property of a capacitor. Similarly, the inductive reactance is a property of an inductor.
An ideal resistor has zero reactance while it's a purely resistive element. On the contrary, perfect capacitors and inductors have zero resistance. So, strictly speaking, there is no such thing as capacitor resistance. We usually treat this phrase as a mental shortcut for the capacitive reactance. As we've mentioned in the previous section, the capacitive reactance is a capacitor's property that opposes alternating current.
The same is true for any set of capacitors that we can arrange in series or parallel. One of the crucial properties of AC is its frequency f.
We can calculate the capacitive reactance X of a capacitor C using the following equation:. As you can see, the higher the frequency of the capacitance , the lower the reactance. Does it make sense? Remember that a capacitor stores electric energy.
While it's charging, it looks like the capacitor passes the current almost freely. The more it can absorb the higher the capacity , the less it resists to let the current flow. Additionally, when the AC frequency gets higher, the less time there is for the capacitor to charge fully. There is nothing challenging about estimating the capacitive reactance of any capacitor.
Let's practice the computations with an example. The resultant combination of resistance and inductive reactance is referred to as impedance and this is again measured in ohms. When using and designing circuits that contain inductors it is often necessary to look at the inductive reactance, calculate it using the formulas above and then add this to a pure resistance to gain the overall impedance.
As such these formulas are particularly useful. The degree to which the inductor impedes the flow of current is due to its inductive reactance. Inductive reactance The effect by which the current flow of an alternating or changing current in an inductor is reduced is called its inductive reactance.
Inductive reactance formulas Although there is perfect inductors do not exist, it is helpful to imagine one to look at the formulas and calculations associated with inductors and inductance. Read more about. Shopping on Electronics Notes Electronics Notes offers a host of products are very good prices from our shopping pages in association with Amazon. Note: Electronics Notes receives a small commission on sales at no cost to you.
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