As the frequency of an ac circuit increase , the current first increas...
Option(3) is correct because this happens in LCR circuit where on increasing frequency impedance of the LCR circuit first decreases because at low frequency Xc is greater than XL and on slowly increasing frequency Xc decreases slowly first and XL increases slowly because Xc is inversely proportional to frequency and XL is directly proportional to frequency and so the difference between Xc and XL decreases first and so impedance decreases first and so current increases first... at resonance frequency Xc becomes equal to XL and on further increasing frequency above resonance frequency XL goes on increasing and Xc goes on decreasing and so the difference between XL and Xc increases and so the impedance increases which results into decreasing current....
so yes on increasing frequency first impedance decreases,current increases and then after resonance frequency impedance increases and current decreases.
As the frequency of an ac circuit increase , the current first increas...
Introduction:
In an AC circuit, the behavior of current with respect to frequency depends on the combination of circuit elements present. Let's explore the different possibilities and determine the most likely combination of circuit elements that would lead to an increase and then a decrease in current as the frequency increases.
Possible combinations of circuit elements:
1. Resistor and inductor:
- When an AC voltage is applied to a resistor, the current through it is in phase with the voltage.
- In an inductor, the current lags the voltage by 90 degrees.
- As the frequency increases, the inductive reactance (XL) also increases, causing the current to decrease.
- Therefore, in this combination, the current would continuously decrease with increasing frequency. It does not exhibit the desired behavior.
2. Resistor and capacitor:
- When an AC voltage is applied to a capacitor, the current through it leads the voltage by 90 degrees.
- In a resistor, the current is in phase with the voltage.
- As the frequency increases, the capacitive reactance (XC) decreases, leading to an increase in current.
- However, the current would continue to increase as the frequency further increases. It does not exhibit the desired behavior.
3. Resistor, inductor, and capacitor:
- This combination is known as an RLC circuit or a resonant circuit.
- At certain frequencies, called resonant frequencies, the reactances of the inductor and capacitor cancel each other out, resulting in a minimum impedance.
- At these frequencies, the current is primarily determined by the resistance in the circuit.
- As the frequency increases from the resonant frequency, the inductive reactance dominates, causing the current to decrease.
- Therefore, in this combination, the current first increases and then decreases with increasing frequency, which matches the desired behavior.
4. None of these:
- This option can be chosen if there are other circuit elements or configurations that exhibit the desired behavior.
- However, based on the given options, the combination of a resistor, inductor, and capacitor (RLC circuit) is the most likely to comprise the circuit.
Conclusion:
Based on the behavior of current in an AC circuit as the frequency increases, the most likely combination of circuit elements that would exhibit an increase and then a decrease in current is a resistor, inductor, and capacitor (RLC circuit). This combination allows for the desired behavior due to the interplay of the reactances of the inductor and capacitor at certain frequencies.
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