The question involves understanding the behavior of elements in an L-C-R circuit, particularly how reactances change with frequency. Let's break down each statement:
- Statement: L and R oppose each other
- This statement is incorrect. In an L-C-R circuit, L (inductance) and C (capacitance) are reactive components, while R (resistance) is a resistive component. Resistance does not "oppose" inductance; instead, resistive and reactive components contribute to the total impedance of the circuit through different mechanisms.
- Statement: R value increases with frequency
- This statement is incorrect. The resistance (R) of a material is typically independent of frequency in normal operation. It's the reactances (inductive and capacitive) that vary with frequency.
- Statement: The inductive reactance increases with frequency
- This statement is correct. The inductive reactance \(X_L\) is given by \(X_L = 2\pi f L\), where \(f\) is the frequency and \(L\) is the inductance. As frequency \(f\) increases, \(X_L\) increases proportionally. This is why inductors oppose changes in current more strongly at higher frequencies.
- Statement: The capacitive reactance increases with frequency
- This statement is incorrect. Capacitive reactance \(X_C\) is given by \(X_C = \frac{1}{2\pi f C}\), where \(f\) is the frequency and \(C\) is the capacitance. As frequency \(f\) increases, \(X_C\) actually decreases. Therefore, capacitors are more effective at higher frequencies.
Based on this analysis, the correct statement is: The inductive reactance increases with frequency.