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An electromotive force (e.m.f.) is the open-circuit, or no-load, potential difference provided by a source -such as a battery or generator. For a closed circuit, an e.m.f. is the sum of the voltage-drops around any closed loop, including the internal voltage drop of the source.
A potential difference (voltage) can exist across any circuit component. For example, the fact that current is flowing through each of several resistors in a series circuit means that there must be an individual potential difference across each of those resistors (which we also term 'voltage drop').
An electromotive force is the name we give to the open-circuit potential difference provided by a generator, battery, etc. For example, the open circuit potential difference of a battery would be its electromotive force.
So, if we use a series resistive circuit as an example, the battery would provide the electromotive force, while voltage drops would then appear across its internal resistance, and across each of the resistances. The magnitude of the electromotive force is then equal (but acting in the opposite sense) to the sum of the voltage drops, including the internal voltage drop.
Many textbooks use the symbol, E, to represent an electromotive force, and V to represent potential difference. So, Kirchhoff's Voltage Law, for example, will often be seen written as: E = V1 + V2 + V3 + etc.
1) EMF of a battery is the amount of electrical energy required to move a unit positive charge from the negative to the positive terminal of the battery when the battery is open circuited, whereas, potential difference across the terminals of a battery is the energy required for the same process but when the battery is in use, that is, current is flowing through it.
2)Since when current flows through the battery, some amount of energy is lost in overcoming the internal resistance of the battery, the difference in energy between the two terminals of the battery is somewhat less that it is when current does not flow. Hence, EMF is always greater than potential difference and is the sum of potential difference and the energy lost due to internal resistance.
3)While talking about a circuit, EMF is an independent variable and is the voltage that causes current( i=v/r ) but potential difference is a dependent variable and is the voltage between two points of the circuit as an effect of a current ( v=i*r ).
4) EMF is constant and independent of the resistance of circuit whereas potential difference varies.
5)The source of EMF is that part of a circuit where electrical energy is created from any other form of energy,but potential difference is said to exist in that part of the circuit where electrical energy is converted in to any other form of energy.
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What is the potential difference between two points in a circuit is called?
Voltage drop
Difference between back EMF and induced EMF?
An induced electromotive force (emf) is an induced voltage. Voltage (emf) causes current flow, and this induced voltage will cause a current that is called the induced current.We might also add that the induced current will cause a magnetic field to expand about the current path, and this field will "sweep" the conductor. The sweeping of the conductor by that expanding magnetic field will set up an emf that will oppose the emf that was creating it.CommentTechnically, there is no such thing as an 'induced current'. It is voltage that is induced. Any current flows as a result of that induced voltage being applied to a load. But that current is certainly NOT induced!
Why do you measure emf with a potentiometer not with voltmeter?
EMF (E''electromotive Force'') is another term for Volts, hence the E in electronic formulas and EMF is measured with a volt meter. A potentiometer is not a meter at all, it is a variable resistor
How does voltage drop related to impressed emf?
Voltage drop is resultant of IR ie current and the line resistance, not dependent on impressed emf
What is potensional difference PD EMF or voltage measured in?
They are each measured in volts (V).
What is the potential difference between two points in a circuit is called?
Voltage drop
Difference between voltage and emf?
'Voltage' is simply another term for 'potential difference', and an electromotive force is the open-circuit, or no-load, potential difference of a source such as a battery or generator.
Another name for EMF?
"Potential difference" or "Voltage".
What are the differences between potential difference and emf?
Potential difference is the difference in electric potential energy between two points in a circuit, while electromotive force (emf) is the total energy provided per unit charge by a battery or voltage source. In other words, potential difference measures the voltage drop across a component in a circuit, while emf represents the energy per unit charge supplied by the source.
Difference between back EMF and induced EMF?
An induced electromotive force (emf) is an induced voltage. Voltage (emf) causes current flow, and this induced voltage will cause a current that is called the induced current.We might also add that the induced current will cause a magnetic field to expand about the current path, and this field will "sweep" the conductor. The sweeping of the conductor by that expanding magnetic field will set up an emf that will oppose the emf that was creating it.CommentTechnically, there is no such thing as an 'induced current'. It is voltage that is induced. Any current flows as a result of that induced voltage being applied to a load. But that current is certainly NOT induced!
It can be said that pressure and electromative force are the same?
There is analogy between pressure and EMF or voltage. What pressure is to the liquids, EMF or voltage is to electric current. But, of course, they are not the same.
A device that provides an emf?
An example of a device that provides an electromotive force (emf) is a battery. A battery produces a voltage difference between its terminals, which creates an electric current when connected to a circuit. This emf is the driving force that pushes electrons through the circuit.
What symbol is used to measure potential difference?
V which abbreviates the word volt, which is the unit of measure of the difference in electromotive force (EMF), (or electric potential) between two points of contact; the resulting voltage difference could be direct current (DC) or alternating current (AC) depending on the source of the voltage difference.
Can terminal potential difference be greater than the emf supplied?
No, the terminal potential difference cannot be greater than the emf supplied. The emf represents the maximum potential difference that the cell or battery can provide, while the terminal potential difference is the actual potential difference across the terminals when a load is connected.
What is the term for he phenomenon of emf development between two different metals placed in contact?
The term for the phenomenon of emf development between two different metals placed in contact is called the thermoelectric effect. This effect occurs because of the temperature difference between the two metals, which creates a potential difference or voltage.
What are the differences between emf and voltage drop?
emf and voltageAnswerElectromotive force is the potential difference created by a source, such as a battery or generator, when it is not connected to a load -in other words, on 'open circuit'.Voltage drop is the potential difference across a load, such as a resistor, which causes current to flow through that load.A voltage drop occurs, internally, in batteries and generators, when they are supplying a load. The battery or generator's terminal voltage, when supplying a load, is its e.m.f. less its internal voltage drop.
Another word for voltage?
electromotive force (abbreviation: EMF or emf)
