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Typically, while examining the theory underlying electrical circuits, it is believed that all of the circuit components are perfect in their performance. A zero resistance battery is believed to exist in an ideal condition for the system’s battery in this case. However, this is not so in practice. When dealing with batteries in the real world, it has been discovered that they contain some internal resistance, which affects the current flowing through the system. The voltage is often not indicated on the battery and it varies when the battery charges and when discharging occurs. In this situation, it becomes important to measure the internal resistance of a cell.
What is a Cell?
In a cell, the potential difference between two electrodes is maintained by the chemical processes between them. The term “battery” refers to a group of two or more cells linked in series or parallelly. It is essential in meeting voltage requirements. Energy from a battery can be converted from chemical energy to electrical power. This is known as an electrochemical cell. Batteries allow us to power things without the need for connections and wires. They generate electricity when linked to a circuit. Let us take a look at what the internal resistance of a cell depends on.
What is the Internal Resistance of a Cell?
Batteries and power sources generally include an internal resistance that may restrict the amount of voltage provided to an external load. A cell’s positive and negative terminals are connected by an external circuit, which transmits electricity from one end of the circuit to the other. The cell’s electrolyte must flow from its negative terminal to its positive terminal in the direction of the flowing current. The cell’s electrolyte provides resistance to current flow throughout this phase within the cell. This is referred to as the internal resistance of a cell.
Derivation of the Formula for Internal Resistance of a Cell
Consider a circuit. Internal resistor with resistance r linked in series may be used to alter the cell’s output voltage. An external resistor R is connected across the circuit’s load path. Terminal potential difference (V) is the potential difference between the cell’s positive and negative terminals while current flows through the circuit. For example, a battery may have an EMF (Electromotive force) of 1.60 volts, but not all of this will be applied to an external load.
In this context, internal resistance refers to a cell or battery’s resistance to current flow, which results in heat creation. Ohms are used to measure the internal resistance. According to this formula, the internal resistance of a cell is related to its electric current.
e = I (r + R)
A cell has an internal resistance of r measured in ohms, equal to the cell’s EMF or electromotive force.
e =IR + Ir or V + Ir = e
When the current (I) flows through the circuit, V is the potential difference (terminal) across the cell. This is true because the emf of a cell is higher than the difference in potential across a cell.
What is a Potentiometer?
The potential difference between two points is quantified using “potential.” It may also be used to test the internal resistance or compare the e.m.f. of two cells. It’s a 10m long wire with a consistent cross-sectional area that serves as the device’s structural foundation. Before utilising it, one must ensure that the wire used in a potentiometer has a consistent cross-sectional area, low resistance and a high-temperature coefficient. In a series, the copper strips are used to connect the wires stretched in parallel. The wooden board has a metre scale connected to it as well.
What are the Chemical Reactions Occurring in a Cell?
The cathode accepts electrons from the anode’s negative terminal and works as an oxidising agent. By releasing electrons, the anode functions as a reducing agent. Thus, the anode and cathode are electrically different due to these chemical processes. Anode-to-cathode electron flow is impeded by the electrolyte when there is no electricity. For this reason, we’re relying on an external source or a circuit. When the circuit is closed, electrons flow from the anode to the cathode. Finally, the device that is linked to it receives electricity.
Conclusion
In a circuit, cells may be linked in series or parallel. It creates a higher voltage for the cells linked in series. It is easy to identify and replace the damaged cells as the circuit is broken. When a single cell in the circuit is compromised, the whole link might be compromised. The cells that are joined in series are quickly depleted. Thus they don’t survive as long as they would otherwise. For residential use, it is not necessary. When a battery is attached to a circuit, it creates an electrical resistance called Internal Resistance of a Cell.
