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Actually when the permanent coil dc motor rotates in magnet field by providing current an emf is induced in coil in the opposite direction of current in the coil by faraway law. this result in a torque in opposite direction.
for example he the applied voltage is 10volts and the resistance is 10ohms theories current would be 10A. it is at time is zero it means when the switched is just on or circuit is just closed.
if the induced emf is 10volts them the effective voltage will be 90volts. now he we calculate the current by ohms law the current will be 9A. This shows that at time is equal to zero the naughty current is passing through coil as the time pass amount of current passing through the coil will become less or minimum. As current and force are direct related the torque will become minimum. here the angular acceleration is decreasing it is not retarded.
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Why we don't use starters for small motors?
When motor is started it has low speed which does not produce back emf hence very large current is drawn by the motor which may destroy the coil inside.small motors gain speed very quickly they produce back emf very fast at start hence they do not require starter.
How do you prove the existence of back EMF?
How do you proof of the existence of back emf ?
What does the emf equation of asingle phase transformer do?
The emf equation of signal phase transform
What is the meaning of E in electric generators?
E is normally back emf ,v is supply voltage as per machine theory ......for generator E>v for motors V>E ......................................back emf will be in armature of machine.....................................................AnswerUnfortunately, if you are referring to the symbol for voltage, then there is no standard. The above answer is correct for some texts but, often, 'E' represents 'electromotive force', which is the open-circuit potential difference of the generator.
Does motional emf call induced emf?
yes indused emf is also called motional emf. If an open coil is subjected to a variable magnetic field, at the ends of the coil a potential difference is induced which is called induced emf. If a coil is connected to an emf source and switched on, the rising current will produced an variable magnetic field which in turn produces an emf. It is called back emf.
Why we don't use starters for small motors?
When motor is started it has low speed which does not produce back emf hence very large current is drawn by the motor which may destroy the coil inside.small motors gain speed very quickly they produce back emf very fast at start hence they do not require starter.
How do you prove the existence of back EMF?
How do you proof of the existence of back emf ?
When the rheostat position is changed from minimum position to maximum position in motors what will happens?
the back emf increases so that high currents doesn't pass through the field windings
What does the emf equation of asingle phase transformer do?
The emf equation of signal phase transform
Can back emf in an inductor be in the same sense as emf of source?
yes..only the application is different.
What is the meaning of E in electric generators?
E is normally back emf ,v is supply voltage as per machine theory ......for generator E>v for motors V>E ......................................back emf will be in armature of machine.....................................................AnswerUnfortunately, if you are referring to the symbol for voltage, then there is no standard. The above answer is correct for some texts but, often, 'E' represents 'electromotive force', which is the open-circuit potential difference of the generator.
Does motional emf call induced emf?
yes indused emf is also called motional emf. If an open coil is subjected to a variable magnetic field, at the ends of the coil a potential difference is induced which is called induced emf. If a coil is connected to an emf source and switched on, the rising current will produced an variable magnetic field which in turn produces an emf. It is called back emf.
What is Counter Force?
It is also called back EMF. Back EMF is the electric potential difference that opposes the current that induces it. See related link below.
Why two point starter used in dc series motor?
The only explanation to that is given by the presence of back emf Eb, which plays a critical role in governing the operation of the motor. The back emf, develops as the motor armature starts to rotate in presence of the magnetic field, by generating action and counters the supply voltage. This also essentially means, that the back emf at the starting is zero, and develops gradually as the motor gathers speed. The general motor emf equation E = Eb + Ia.Ra, at starting is modified to E = Ia.Ra as at starting Eb = 0.
What is Back emf of DC motor?
In dc motor, the armature conductors are revolving in the magnetic field and emf is induced in the armature conductors. The direction of the induced emf is in opposite direction to the applied voltage as per Flemings left hand rule. So, the induced emf in motor is called as back emf or counter emf. Vydehi
What is counter electro-magnteic force?
It is also called back EMF. Back EMF is the electric potential difference that opposes the current that induces it. See related link below.
What is emf induced in a motor's coil that tends to reduce the current in the coil of the motor?
BACK emf induced in a motor's coil that tends to reduce the current in the coil of the motor. The answer should be 'back'.
