The relationship between frequency and reactance are expressed by the equations:Īt the lower frequency most of the opposition is X C or capacitive reactance and at the higher frequencies the opposition is mainly X L or inductive reactance. Capacitive reactance on the other hand is inversely proportional to frequency so, as the frequency increases the value of X C decreases. Inductive reactance is directly proportional to frequency, if the frequency being applied to the circuit is increased there would be an increase in X L.
As shown in the graph below, the impedance of an AC circuit varies with frequency. This takes into account the opposition of the resistor ( resistance R), the opposition of the inductor ( inductive reactance or X L), and the opposition of the capacitor ( capacitive reactance or X C).
#BANDWIDTH METER SERIES#
In the series RLC network the impedance is defined by the equation: The frequency of this voltage and current is called the resonant frequency, and is defined as the frequency at which a given system or object will respond with maximum amplitude. The circuit is said to be resonant when the frequency of the applied voltage is adjusted to produce maximum current while the magnitude of the voltage is held constant.
A series-resonant circuit offers low impedance to the flow of current at a particular frequency. The current in the circuit can be measured with a meter or, we could calculate the current using a form of Ohm's law, which is – current (I) equals the applied voltage (E) divided by impedance or total opposition in the circuit (Z), i.e. Most commonly, we use one particular AC voltage: 120 volts 60 Hz, but in this case we're very interested in the frequency being variable so it would be some value other than 60 Hz. The voltage source represented by an AC symbol, is also variable in frequency. The resonant circuit below consists of a resistor, an inductor and a capacitor in series with a current meter and a voltage source. Resonance can be obtained in either series or parallel circuits containing three electrical characteristics namely resistance, inductance and capacitance. A resonant circuit has a specific frequency and bandwidth and we put that to use in the radio receiver. Another name for the tuning circuit is a resonant circuit. When you turn on a radio and you try to select a radio station, what you're doing is using the bandwidth characteristics of a tuning circuit in the radio to select your particular station. To help understand bandwidth further let’s think about a radio. Bandwidth is defined as the size of frequency range that is passed or rejected by the tuned circuit. An important property of a resonant circuit is its bandwidth.
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