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EMF Physics - Important Notes for Engineering Entrance Exams
IMPORTANT LINKS
Electromagnetic Induction
EMF is indeed a very important topic in Physics, considering the engineering entrance exams point of view. This article aims at educating the students about the basics of EMF in a simplified form. Let’s understand the terminologies associated with it.
Terminologies
First on the list is electric potential. It is defined as the work done to move an electric charge from one point to another. During this displacement process, an electric field is created by the charged particle. The work which is to be done in moving that particle is against this electric field and hence is represented as a negative component of electric force. If a particle is moved from a to b, then mathematically it is represented as follows:
A device has been created which maintains a particular value of electric potential between the two electrodes. It is known as a cell and the collection of two or more cells in a particular alignment (either in series or in parallel) is known as a battery. the unit of electric potential is volt, which is named in honor of Alessandro Volta who was the inventor of the electric battery. A cell converts energy generated through chemical reactions into electric energy and hence it is sometimes also called an electrochemical cell.
Related Article- Electric Currents & its Effects
The term electrode is used to represent the two termini of the cell from where the electrons are moving. The electrodes are cathode and anode. The cathode termini deliver the electrons while the anode collects them.
Now, as we have understood all the basic components of a cell, let us talk about EMF now. Emf or Electromotive Force is the output generated by a battery. It is the potential difference created between the two terminals in the absence of current. Mathematically, it is given by energy which is required to displace the charge divided by per unit charge in coulombs.
EMF AND Terminal Voltage
Now, comes the concept of the terminal voltage. It is defined as the potential difference across the cell. When the cell is not connected to any external circuit, then this terminal voltage is equal to the emf of the battery. But when a cell or battery is a part of the circuit then the terminal voltage is given by the voltage difference across the circuit.
This diagram represents an open circuit when the terminal voltage is equal to the emf of the cell.
This diagram represents a closed circuit. The terminal voltage across a closed circuit can be calculated by the formula:
EMF = v +V
EMF = Ir + IR
v: voltage within the cell
V: voltage in the external circuit
r: internal resistance
R: resistance in the external circuit
No system in this world is ideal. Hence, this electric circuit also faces some loss in energy due to the presence of internal resistance. Internal resistance is the resistance generated within a battery due to electrolytes and electrodes. This resistance acts as a barrier for the flow of current is the reason behind voltage drop. The circuit represented above emf and internal resistance experiment to calculate the true potential drop in a circuit or internal resistance
Summarised Notes about EMF
- Alessandro Volta is the inventor of the battery.
- SI unit of potential difference is volt
- EMF is the energy required in joules to move per unit charge of coulombs between two termini of an energy source. The value of the emf of a battery is calculated in an open circuit.
- Terminal voltage is termed as a potential difference across the cell in a closed circuit. It is less than emf because of the internal resistance created by electrolytes and electrodes of the cell.
So, this is all about the EMF. Get some practice of the same on our free Testbook App. Download Now!
Emf Physics FAQs
What is EMF?
EMF (Electromotive Force) is a measure of the energy supplied by a source per unit charge that flows through it.
What is the unit of EMF?
The unit of EMF is the Volt (V).
What is the difference between EMF and potential difference?
EMF is the energy supplied by a source per unit charge that flows through it, while potential difference is the energy required to move a unit charge between two points in a circuit.
What is the source of EMF in a circuit?
The source of EMF in a circuit is typically a battery, generator, or other electrical power source.
What are some common applications of EMF?
EMF is used in a variety of applications such as in the design of electrical circuits, batteries, and generators, and in technologies such as solar cells and fuel cells.
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