# How do you calculate the emf of a motor?

Contents

## What is the emf equation of a motor?

As the armature rotates, a voltage is generated in its coils. In the case of a generator, the emf of rotation is called the Generated emf or Armature emf and is denoted as Er = Eg. In the case of a motor, the emf of rotation is known as Back emf or Counter emf and represented as Er = Eb.

## How do you calculate back emf of a motor?

The power from each device is calculated from one of the power formulas based on the given information. The back emf is ϵi=ϵS−I(Rf+REa)=120V−(10A)(2.0Ω)=100V. Since the potential across the armature is 100 V when the current through it is 10 A, the power output of the motor is Pm=ϵiI=(100V)(10A)=1.0×103W.

## How do you calculate the emf of a dc motor?

EMF equation of a DC generator

1. Average emf generated per conductor is given by dΦ/dt (Volts) … eq. …
2. Flux cut by one conductor in one revolution = dΦ = PΦ …. (Weber),
3. Number of revolutions per second (speed in RPS) = N/60.
4. Therefore, time for one revolution = dt = 60/N (Seconds)
5. From eq.

## What is the formula of flux per pole?

Flux= 2πr*l*B. now, for calculating flux per pole, divide it by P=4. So, Flux per pole after substituting all values is equal to 0.0188 Wb.

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## What is emf of 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 emf equation of alternator?

V = 4.44 Kf KC KD f ΦT Volts.

Where: V = Actual generated Voltage per phase.

## Is back EMF AC or DC?

Back EMF can have either a sinusoidal (AC) or a trapezoidal (DC) waveform. The shape of the back EMF is important, as it determines the type of drive current and commutation method that should be used for the motor.

## What is back EMF of a motor?

Back EMF is the system in the coil of an electric motor that opposes the current flowing through the coil, when the armature rotates. When the speed varies, the winding characteristics may fluctuate, resulting in variation of back EMF.

## Why back emf is used in DC motor?

When the armature of the DC motor rotates under the influence of driving torque, the armature of the conductors moves through a magnetic field inducing an emf in them. The induced emf is in the opposite direction to the applied voltage and is known as the back emf.

## What is emf in a DC motor?

A motor has coils turning inside magnetic fields, and a coil turning inside a magnetic field induces an emf. This emf, known as the back emf, acts against the applied voltage that’s causing the motor to spin in the first place, and reduces the current flowing through the coils of the motor.

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