Potential Difference and EMF of a Cell

A cell or an electrochemical cell are devices applied for developing electrical energy from chemical processes or vice versa. EMF stands for Electromotive Force and is measured in coulombs of charge. It is created by pressure or an electric intensity due to electrical energy or a source. 

Internal resistance is the barrier to the passage of current provided by the cells and batteries, resulting in heat development. Ohms are used to measure the internal resistance.

 Cells, EMF and internal resistance are the components that complete the circuit and aid in the passage of electricity. Cells, EMF and internal resistance are all interrelated. Batteries, or cells, have internal resistance, potential difference or voltage.

Cells

A cell, sometimes known as an electrochemical cell, is a device that can generate electrical energy from chemical processes or vice versa. You’ve probably seen a cell, the little AAA or AA batteries we use in our remote controls.

An electric battery is a device composed of two or more cells that transform the chemical energy contained in the chemicals into electrical energy. A battery gives a constant stable current source to an electrical circuit or equipment by supplying constant EMF or Electromotive force.

Each cell comprises two half-cells linked together by a conductive electrolyte comprising anions and cations. The electrolyte and the negative electrode, the anode, comprise one half-cell. 

Anions or negatively charged ions move to the anode. The second half-cell contains electrolyte and the cathode, a positive electrode to which cations (positively charged ions) flow.

The battery is powered by redox processes, which include reduction and oxidation. Cations are reduced during charging (they acquire electrons) at the cathode, whereas anions are oxidised (they lose electrons). 

The procedure is reversed during discharge. The electrodes do not come into contact but are electrically coupled through the electrolyte. They are very useful as they can turn chemical energy into electrical energy and vice versa.

Cells that generate electricity

There are several varieties of cells accessible, some of which are as follows:

• Hydrogen Fuel Cells

• Secondary Cells

• Cells Galvanic

• Photovoltaic (PV) Cells

• Cells of Storage

• Primary Cells

These are the cells that can generate electricity through various processes. Each operation varies depending on the type of the cell. We can see different variations of these cells in our day-to-day life, as we use them for different purposes.

EMF

In electromagnetism, an electromotive force is calculated in volts. It indicates the electrical activity of the nonelectrical source. Devices, such as batteries or generators, generate an EMF by converting various energy sources into electrical energy.

EMF stands for electromotive force and is measured in coulombs of charge. It is created by pressure or an electric intensity due to electrical energy or a source. It is a device that transforms any energy into electrical energy that is then measured in coulombs of charge. EMF or ElectroMotive Force, is indicated by the mathematical symbol E.

I (R + r) = emf

Where I denotes the current in amperes, R denotes load resistance in the circuit in ohms and r denotes internal resistance in ohms.

E/Q = emf

Where E denotes energy in joules and Q denotes charge in coulombs.

When connecting an appliance to a battery, a current proportional to the voltage flows through the circuit. The device’s resistance is defined as the ratio of the voltage (V) across it to the current flowing through it due to the potential. 

Friction in Mechanics is related to resistance to electricity. The electrical resistance is how difficult it is to conduct an electric current through it. Electrical resistance has resulted in the development of electrical warmers and induction cooktops. 

Internal Resistance

There is internal resistance when there is current in the device or electrical circuit and a voltage drop in the source voltage or battery. It is caused by electrolytic material in batteries or other sources of electricity. Internal resistance is interrelated to E and V.

(E – V)/I = Internal Resistance (r)

Where E is the device’s emf, V is the potential difference between the devices and I is the device’s current. Internal resistance is the result of battery resistance or buildup in the battery. The equation given below is used to arrive at this conclusion:

V = (E – Ir)

The following are the relationships between a cell’s internal resistance, represented by r and emf, denoted by e:

I (r + R) = e

We can see that the term marked by the letter e = EMF, known as the electromotive force of Volts expressed as I = current denoted by A, the letter R = Load resistance and the letter r represents the internal resistance of a cell measured in ohms. 

Internal resistance is a type of resistance that exists between the electric power supply terminals. Internal resistance causes changes in the circuit and wastes some electrical energy in the electric power supply itself. When a current is delivered, the power supply becomes heated.

Conclusion

Cells, EMF and internal resistance have many applications. Electrochemical cells are utilised in flashlights, digital clocks, military uses, corrosion prevention and other applications. Electrolytic cells manufacture high-purity lead, zinc, aluminium and copper. 

They use it to look for microscopic levels of metal ions in a solution. The major application of emf measurement is to detect the endpoint of a titration by measuring the emf of a cell consisting of an indicator electrode (electrode whose potential is dependent on the molarity of reactant ions) and a reference electrode (e.g., SCE) as the titration progresses. We hope this article will give a great idea of the Cells, EMF and internal resistance.