Why do we use a resistor in an RC circuit?
The capacitor and the resistor in series serve as a transient voltage suppressor and suppress voltage peaks. the capacitor absorbs the excessive loads and the resistance makes it possible to control the discharge.
A rc series circuit with the capacitor before the resistance, taking the voltage across the resistor creates a high-pass circuit, which means that only the high frequencies can pass the circuit. This can be used to filter the continuous offset or low frequency noise.
A good reason is that the resistance of the capacitor wires is not known. As a result, the addition of a resistance overwhelms this phenomenon and the value of the resistance is now known. the resistance hinders the flow of charge, which makes it possible to know a cycle of discharge in time, which is very useful and is the reason why a circuit rc exists.
For one, a charge capacitor with a resistor to prevent the charge will take some time to reach a certain charge (or potential, aka voltage). This can be used to delay activation or deactivation of a switch. similarly, the discharge time may be used for similar purposes, and therefore it may also be used for any purpose where a delay is required.
The time constant is therefore the basis on which filtering works. the value of rc is the definition bit of a filter and is used in the filter equation. this is the basic for an RC circuit.
In practical terms, unloading or charging a capacitor without any resistance will result in a large load flow, as well as the risk of burn-out of printed circuit boards, lead soldering, fires and possibly other effects. undesirable.
How does an RC circuit work?
Conceptually, the resistor is there to damp the charge / discharge path around the capacitor.
consider the two most common passive RC networks: the low-pass and high-pass configurations. Consider also a source signal that, when enabled, applies 5 VDC to its output terminals and, when disabled, returns to zero volts.
low-pass configuration:
in a low-pass configuration, a serial network is built with the capacitor grounded on one side. the input signal of the voltage source is applied to one end of the resistor and the output is taken between the resistor and the cap.
the source is disabled and applies 0v to the system. when the source is on, the 5v is applied to the RC network. the sudden pulse introduces high frequencies into the system, but these are counteracted by the ability of the capacitor to transmit these high frequency transient AC signals to the earth. during this time, the DC voltage increases to 5V in a standard time (usually in time constants). Thus, the role of resistance is to attenuate high frequency AC transients.
High-pass configuration:
in a high-pass configuration, a serial network is built with the resistance grounded on one side. the input signal of the voltage source is applied to one end of the capacitor and the output is taken between the cap and the resistor.
the source is disabled and applies 0v to the system. when the source is on, the 5v is applied to the RC network. the sudden pulse again introduces high frequencies into the system, but this time they pass through the capacitor into the output signal.
The reason they pass is because a resistor does not have complex impedance properties (like a cap or inductor), so the high frequencies are felt through the resistor.
This jump to 5v is perceived as a high frequency blip at the output and a return to a continuous output voltage of 0v.
Indeed, when the hood sees the 5v on one of its plates, the current passes immediately through the resistor to charge the other side of the cover to zero the electric field between its plates. in this way, the capacitor blocks the DC voltage.
