# What is EMF in DC motor?

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## What is emf in a 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.

## What is DC emf?

A Direct Current (DC) electromagnetic field refers to a constant or static DC electric or DC magnetic field emission which has a frequency of 0 Hz. … DC magnetic fields can also be created from a DC power source of electricity such as battery power, solar power and wind power.

## 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 generated emf?

When the armature of a DC generator rotates in magnetic field, an emf is induced in the armature winding, this induced emf is known as generated emf. It is denoted by Eg.

## 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.

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## Does DC have emf?

Most power systems operate with alternating current (AC). But there are some direct current (DC) power lines, which produce DC or static EMFs.

## What is the difference between emf and back 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.