The so-called terminal voltage of a battery is lower than the emf when it is discharging because of the voltage drop across the internal resistance .
Can emf be less than terminal voltage?
Yes it can , for example when a cell is being recharged the terminal pd is V=E+IR where E is the emf of the cell, I is the current passing through the cell from positive to negative terminal and R is the internal resistance of the cell.
Why is terminal voltage different from emf?
E.m.f. is the maximum potential difference that can be delivered by a cell or a generator when no current flows through it. ... Terminal voltage is always lesser than the emf of the cell. It is because of the drop in potential because of the current passing through the internal resistance of the cell or the generator .
What is the formula for electromotive force emf?
| varepsilon electromotive force | E the energy in the circuit | Q Charge of the circuit. |
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Can voltage be greater than emf?
They really test the internal resistance of the battery. ... The voltage output of the battery charger must be greater than the emf of the battery to reverse current through it . This will cause the terminal voltage of the battery to be greater than the emf, since V = emf − Ir, and I is now negative.
What is relation between emf and voltage?
| EMF Voltage | Emf is the voltage developed between two terminals of a battery or source, in the absence of electric current. Voltage is the potential difference developed between the two electrode potentials of a battery under any conditions. |
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Is terminal voltage greater than emf?
The emf of a cell is greater than terminal voltage because the potential difference between the two terminals is not connected to any of the circuit. If it connects to the circuit then the voltage is automatically reduced because of the internal resistance.
What is difference between voltage and emf?
Voltage is the potential difference between two points which causes current to flow. It is the amount of energy per unit charge while moving between two points. EMF or electromotive force is the amount of energy supply to the charge by battery cell.
What is SI unit of emf?
Like other measures of energy per charge, emf uses the SI unit volt , which is equivalent to a joule per coulomb. Electromotive force in electrostatic units is the statvolt (in the centimeter gram second system of units equal in amount to an erg per electrostatic unit of charge).
How do you calculate the emf?
The emf is equal to the work done on the charge per unit charge (ε=dWdq) when there is no current flowing . Since the unit for work is the joule and the unit for charge is the coulomb, the unit for emf is the volt (1V=1J/C).
How do you calculate the emf of a coil?
The induced emf in a coil is equal to the negative of the rate of change of magnetic flux times the number of turns in the coil . It involves the interaction of charge with magnetic field.
Is emf greater than potential difference?
Answer: The emf of a cell is always greater than its terminal voltage . ... Because emf is the potential difference across the two terminals of a voltage source when it is not connected to any circuit.
What is back EMF of a cell?
Counter-electromotive force (counter EMF, CEMF), also known as back electromotive force (back EMF), is the electromotive force (voltage) that opposes the change in current which induced it . CEMF is the EMF caused by magnetic induction (see Faraday’s law of induction, electromagnetic induction, Lenz’s law).
What is emf of a cell?
The emf of a cell is the sum of the electric potential differences (PDs) produced by a separation of charges (electrons or ions) that can occur at each phase boundary (or interface) in the cell. The magnitude of each PD depends on the chemical nature of the two contacting phases.
What is the relation between EMF and resistance?
| FORMULAS Related Links | Henry’s Constant Circular Motion Formulas |
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What is difference between MMF and EMF?
When there is a current flow through the conductor coil, a force is produced to drive the magnetic flux or magnetic field lines. This force is called MMF or magnetomotive force. The EMF or electromotive force is the force responsible for the flow of electrons or current in a closed circuit.
