Hi Habeebe. Phase does not vary with amplitude of the input. But output amplitude and phase are both frequency-dependent, so over a limited range there may be a roughly linear correspondence. What are the equations you have where you are interpreting there is such a correspondence?Habeebe said:In an RC circuit, the phase angle between the input and output voltages (not current and voltage) seems to be proportional to the amplitude of the output voltage. That is, as the phase angle between input and output goes to plus or minus 90 degrees, the output voltage goes to 0. Why is that?
Habeebe said:Experimentally. I'm not getting it from equations. If you have a high pass filter, and you run the input voltage to a low frequency, the phase angle will go to about 90 degrees between input and output while the output voltage goes to some small amount. I don't know or really care about the exact relation between the two numerically, but it appeared as though that phase angle difference was somehow related to the change in output voltage. I'm really more interested in what physically is going on that both things happen together.
An RC circuit is a type of electrical circuit that consists of a resistor (R) and a capacitor (C) connected in series or in parallel. The resistor and capacitor work together to control the flow of electric current in the circuit. When a voltage is applied to the circuit, the capacitor charges up to the same voltage as the source, while the resistor limits the flow of current. As the capacitor charges, it creates an electric field, storing energy in the circuit. Once the capacitor is fully charged, it can discharge and release the stored energy back into the circuit.
The phase angle in an RC circuit refers to the difference in timing between the voltage and current in the circuit. It is measured in degrees or radians and indicates how much the current leads or lags behind the voltage. A phase angle of 0 degrees means that the current and voltage are in phase, while a phase angle of 90 degrees means that the current lags the voltage. The phase angle can be measured using an oscilloscope or calculated using mathematical formulas.
The phase angle has a significant impact on the behavior of an RC circuit. A phase angle of 0 degrees means that the current and voltage are in phase, and the circuit behaves like a simple resistor. As the phase angle increases, the circuit starts to exhibit more complex behavior, such as frequency-dependent impedance and energy storage. This can lead to phenomena like resonance and filtering, making the phase angle an essential aspect to consider in RC circuit design and analysis.
In-phase and out-of-phase are two terms used to describe the relationship between the voltage and current in an RC circuit. In an in-phase circuit, the voltage and current are in sync, with a phase angle of 0 degrees. This means that the current and voltage peaks occur at the same time and have the same amplitude. In an out-of-phase circuit, there is a time difference between the current and voltage peaks, with a phase angle other than 0 degrees. This indicates that the current and voltage are not in sync and have different amplitudes.
The phase angle of an RC circuit can be calculated using the following formula: φ = arctan(1/ωRC), where φ is the phase angle in radians, ω is the angular frequency (2πf) in radians per second, R is the resistance in ohms, and C is the capacitance in farads. Alternatively, you can also use a graph or an oscilloscope to measure the phase angle visually. Additionally, there are online calculators and software programs available that can calculate the phase angle for you using input values for R, C, and frequency (f).