We have learned that when two or more capacitors are connected in parallel or in series we can simplify the circuit by replacing a series connection or a parallel connection by a single capacitor with equivalent capacitance. By this method it is possible to reduce some capacitor circuits to a single capacitor.
An ideal capacitor in series with resistance is called Equivalent series resistance of the capacitor. The equivalent series resistance or ESR in a capacitor is the internal resistance that appears in series with the capacitance of the device. Let's see the below symbols, which are representing ESR of the capacitor.
There are several other factors that go into this decision including temperature stability, leakage resistance (effective parallel resistance), ESR (equivalent series resistance) and breakdown strength. For an ideal capacitor, leakage resistance would be infinite and ESR would be zero.
In other words, a capacitor in a circuit technically effects a break in the circuit. Note: Although there are AC capacitors made to take high voltage at either terminal, DC capacitors have definite high and low voltage sides. When a designer of circuitry wants to specify a DC capacitor, he or she uses the symbol shown in Figure 14.1b.
However, there is one complication that requires some thought. The two capacitors in series do not have the same capacitance. Each still carries the same charge, which is the charge on the equivalent of the series combination with capacitance C 12 Once we have the charges Q
Unless it is "leaky," the capacitor in the circuit will have no resistor-like resistance inherent within it. As such, we will assume there is no ir voltage drop across the capacitor. Though there is, in theory, no resistor-like resistance to charge flow associated with the capacitor, capacitors do have a frequency-dependent resistive nature.