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Vishwakarma Government Engineering College (VGEC), Ahmedabad
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Back EMF Solution

STEP 0: Pre-Calculation Summary
Formula Used
electromotive_force = Voltage-(Armature Current*Armature resistance)
ε = V-(Ia*Ra)
This formula uses 3 Variables
Variables Used
Voltage - Voltage, electric potential difference, electric pressure, or electric tension is the difference in electric potential between two points, which is defined as the work needed per unit of charge to move a test charge between the two points. (Measured in Volt)
Armature Current - Armature Current is the Current which Flows in Armature Winding or rotating Winding of Motor or generator. (Measured in Ampere)
Armature resistance - The Armature resistance is given is the opposition that a substance offers to the flow of electric current. (Measured in Ohm)
STEP 1: Convert Input(s) to Base Unit
Voltage: 120 Volt --> 120 Volt No Conversion Required
Armature Current: 0.5 Ampere --> 0.5 Ampere No Conversion Required
Armature resistance: 3 Ohm --> 3 Ohm No Conversion Required
STEP 2: Evaluate Formula
Substituting Input Values in Formula
ε = V-(Ia*Ra) --> 120-(0.5*3)
Evaluating ... ...
ε = 118.5
STEP 3: Convert Result to Output's Unit
118.5 Volt --> No Conversion Required
FINAL ANSWER
118.5 Volt <-- Electromotive Force
(Calculation completed in 00.016 seconds)
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10+ Dc Machine Calculators

Constant Of The DC Machine
constant_of_the_dc_machine = Number of conductors*Number of pole/2*pi*Number of parallel paths Go
Series Generator Terminal Voltage
voltage = Induced voltage-(Armature Current*(Armature resistance+Series field resistance)) Go
Back EMF
electromotive_force = Voltage-(Armature Current*Armature resistance) Go
Shunt Generator Terminal Voltage
voltage = Induced voltage-(Armature Current*Armature resistance) Go
Shunt Field Current
shunt_field_current = Voltage/Shunt field resistance Go
Field Current
field_current = Voltage/Shunt field resistance Go
Armature Current
armature_current = Field Current+Load current Go
Power Generated When The Armature Current Is Given
power = Induced voltage*Armature Current Go
Angular Speed Of The Dc Machine
angular_speed = (2*pi*Motor Speed)/60 Go
Power Generated When Torque is Given
power = Angular Speed*Torque Go

Back EMF Formula

electromotive_force = Voltage-(Armature Current*Armature resistance)
ε = V-(Ia*Ra)

How does back EMF affect supply voltage?

As the back emf depends on the current their value also decreases. The magnitude of the back EMF is nearly equal to the supply voltage. If the sudden load is applied to the motor, the motor becomes slow down. As the speed of the motor decreases, the magnitude of their back emf also falls down.

How to Calculate Back EMF?

Back EMF calculator uses electromotive_force = Voltage-(Armature Current*Armature resistance) to calculate the Electromotive Force, The back emf opposes the supply voltage. The supply voltage induces the current in the coil which rotates the armature. The electrical work required by the motor for causing the current against the back emf is converted into mechanical energy. And that energy is induced in the armature of the motor. Electromotive Force and is denoted by ε symbol.

How to calculate Back EMF using this online calculator? To use this online calculator for Back EMF, enter Voltage (V), Armature Current (Ia) and Armature resistance (Ra) and hit the calculate button. Here is how the Back EMF calculation can be explained with given input values -> 118.5 = 120-(0.5*3).

FAQ

What is Back EMF?
The back emf opposes the supply voltage. The supply voltage induces the current in the coil which rotates the armature. The electrical work required by the motor for causing the current against the back emf is converted into mechanical energy. And that energy is induced in the armature of the motor and is represented as ε = V-(Ia*Ra) or electromotive_force = Voltage-(Armature Current*Armature resistance). Voltage, electric potential difference, electric pressure, or electric tension is the difference in electric potential between two points, which is defined as the work needed per unit of charge to move a test charge between the two points, Armature Current is the Current which Flows in Armature Winding or rotating Winding of Motor or generator and The Armature resistance is given is the opposition that a substance offers to the flow of electric current.
How to calculate Back EMF?
The back emf opposes the supply voltage. The supply voltage induces the current in the coil which rotates the armature. The electrical work required by the motor for causing the current against the back emf is converted into mechanical energy. And that energy is induced in the armature of the motor is calculated using electromotive_force = Voltage-(Armature Current*Armature resistance). To calculate Back EMF, you need Voltage (V), Armature Current (Ia) and Armature resistance (Ra). With our tool, you need to enter the respective value for Voltage, Armature Current and Armature resistance and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.
How many ways are there to calculate Electromotive Force?
In this formula, Electromotive Force uses Voltage, Armature Current and Armature resistance. We can use 10 other way(s) to calculate the same, which is/are as follows -
  • electromotive_force = Voltage-(Armature Current*Armature resistance)
  • shunt_field_current = Voltage/Shunt field resistance
  • armature_current = Field Current+Load current
  • voltage = Induced voltage-(Armature Current*Armature resistance)
  • field_current = Voltage/Shunt field resistance
  • constant_of_the_dc_machine = Number of conductors*Number of pole/2*pi*Number of parallel paths
  • power = Angular Speed*Torque
  • power = Induced voltage*Armature Current
  • angular_speed = (2*pi*Motor Speed)/60
  • voltage = Induced voltage-(Armature Current*(Armature resistance+Series field resistance))
Where is the Back EMF calculator used?
Among many, Back EMF calculator is widely used in real life applications like {FormulaUses}. Here are few more real life examples -
{FormulaExamplesList}
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