1. What is RC Filter Cutoff Frequency?

The RC filter cutoff frequency is the frequency at which the output signal power is half (-3dB) of the input signal power in an RC (resistor-capacitor) circuit. It determines the frequency range that passes through the filter.

2. How Does the Calculator Work?

The calculator uses the RC cutoff frequency formula:

Where:

• \( f_c \) — Cutoff frequency in Hertz (Hz)
• \( R \) — Resistance in Ohms (Ω)
• \( C \) — Capacitance in Farads (F)
• \( \pi \) — Mathematical constant (~3.14159)

Explanation: The equation shows the inverse relationship between cutoff frequency and the RC time constant (τ = RC).

3. Importance of Cutoff Frequency

Details: The cutoff frequency is crucial for designing filters in electronic circuits, determining the frequency range that will be attenuated or passed through the circuit.

4. Using the Calculator

Tips: Enter resistance in ohms and capacitance in farads. For practical values, remember that 1μF = 0.000001F. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What happens at the cutoff frequency?
A: At the cutoff frequency, the output voltage drops to 70.7% (1/√2) of the input voltage, which corresponds to -3dB in power.

Q2: How does changing R or C affect the cutoff frequency?
A: Increasing either R or C will lower the cutoff frequency, while decreasing them will raise it. They have an inverse proportional relationship.

Q3: What's the difference between low-pass and high-pass cutoff?
A: For low-pass filters, frequencies above cutoff are attenuated. For high-pass filters, frequencies below cutoff are attenuated. Both use the same formula.

Q4: Can I use this for RL circuits?
A: No, this formula is specific to RC circuits. RL circuits use a different formula involving inductance (L) instead of capacitance.

Q5: What are typical applications of RC filters?
A: RC filters are used in audio systems, signal processing, power supplies, and anywhere frequency selection is needed in electronic circuits.