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For high frequencies, capacitor acts as
Open circuit
Short circuit
Amplifier
Rectifier
Short circuit
At high frequencies, the capacitive reactance of a capacitor approaches zero, allowing it to behave as an ideal short circuit to alternating current. This occurs because the impedance offered by a capacitor is inversely proportional to the frequency of the applied signal.
At high frequencies, the capacitive reactance of a capacitor approaches zero, allowing it to behave as an ideal short circuit to alternating current. This occurs because the impedance offered by a capacitor is inversely proportional to the frequency of the applied signal.
XCтАЛ=2╧АfC1тАЛ тАФ Capacitive reactance as a function of frequency
Z=R+jXCтАЛ тАФ General impedance of an RC circuit
The impedance of a capacitor is defined by the formula XCтАЛ=2╧АfC1тАЛ. As the frequency f increases towards infinity, the denominator grows, causing XCтАЛ to approach 0╬й. Consequently, the capacitor offers negligible opposition to the flow of high-frequency alternating current, acting as a short circuit.
Capacitors act as open circuits to DC signals (f=0 Hz, XCтАЛтЖТтИЮ).
Capacitors act as short circuits to high-frequency AC signals (fтЖТтИЮ,XCтАЛтЖТ0).
This property is widely used in coupling and bypass capacitors in electronic circuits.
The transition between open and short depends on the time constant ╧Д=RC.
Allows signal coupling in amplifiers while blocking DC bias.
Effective at filtering high-frequency noise when used in shunt.
Idealized behavior; parasitic inductance at very high frequencies makes them behave as RLC circuits.
Real-world capacitors have Equivalent Series Resistance (ESR) that prevents a perfect short.
DC blocking capacitors in audio amplifiers.
High-frequency bypass capacitors in digital IC power supplies.
Coupling capacitors in RF circuits.
At low frequencies, the capacitor blocks current, acting as an open circuit.
The inverse relationship between frequency and reactance is a fundamental principle of frequency-dependent networks.
B is correct тАФ At very high frequencies, the capacitive reactance approaches zero, making the capacitor behave as an ideal short circuit.
Always remember the mnemonic 'CODC' (Capacitor Open for DC) to avoid confusion during rapid exam calculations.