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emf and voltage
AnswerElectromotive 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.
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Why the output voltage drop when the load current is increase?
As the load current increases the losses in the circuit increases (I2R loss) and speed of the generator decreases so the voltage falls a little. and this voltage fall can be adjusted by increasing the speed of the generator and Iron losses are taken as constant losses.
What is the emf induced at zero field current.and what does it signify?
EMF is the voltage across a coil (or motor) due to changes in the magnetic field. If you change the current the coil will generate a voltage (in the opposite direction of the current). So it is not the field but the change that matters.
What happens to the generated voltage of a self excited generator if shunt field resistance is greater than the critical resistance?
it doesn't develop emf ..........
If A generator has an armature resistance of 0.6 ohms and when connected to a load of 40.9 ohms passes a current of 3.5 A what is the terminal voltage and generated EMF?
145.25 v
Which increases or decreases the voltage of alternating current?
(i) EMF (Electro Motive Force) the source of voltage can increase or decrease voltage. (ii) Load connected can increase or decrease voltage (In case of overload voltage reduces.) (iii) Resistance of wire - I R loss ( Voltage drop V = IR)
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 the potential difference between two points in a circuit is called?
Voltage drop
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
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.
Can terminal potential difference be greater than the emf supplied?
All cells have internal resistance. When connected to a load, the resulting load current results in an internal voltage drop across the internal resistance. This voltage drop acts in the opposite sense to the cell's e.m.f., thus causing its terminal voltage to fall below that of the e.m.f. The greater the load current, the greater the difference between the terminal voltage and the e.m.f.
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!
What are the differences between potential difference and emf?
emf is present mainly in battery and potential difference is mainly present in circuit. emf is greater than p.d and p.d is greater than emf.......the units of both are Volt.....
Can the terminal voltage of a battery be larger than its emf?
the voltage of a battery could be larger than the emf if you are to charge the battery, in that case V=E+Ir .
Is emf current greater than current?
EMF is electromotive force. It is another name for voltage. Voltage is electric potential in joules per coulomb. Current is electric flow, in amperes. Amperes are coulombs per second. Voltage and current are not the same thing, and "emf current", or "voltage current" does not make sense.
Can you explain why there is an armature voltage even then the field current is zero in case of separately-excited dc generator?
if this happened it will be due to residual magentism and as soon as this magentism vanishes no voltage will be available , what iam saying can be interpreted mathematically first the generated emf across the armature is given by E= k* flux* speed it is clear due to this equation the emf is directly prportional to the flux which means if the flux is reduced so does the emf and the revers is true, the reduction may be lead to zero flux value and thus the emf (zero field current) secondly this emf covers the terminal voltage and the drop in armature winding if other possiple drops are ignored as E= terminal voltage + armature drop in this equation as E drops down as a result of reducing the flux and which in turn because of reduction in the field current , then right hand components will also drop down until both get zero values , so theoreyically no voltage will be exist at generator terminals when the field current comes to zero value, so the persistance of voltage is due to the residual field and will not last long
What is the Condition for terminal voltage across a secondary cell to be equal to its emf?
in an open circuit, i.e. no current drawn from the cell, producing no drop across its internal impedance
Another name for EMF?
"Potential difference" or "Voltage".
