In nature, emf is generated when magnetic field fluctuations occur through a surface. ... In an electrical generator, a time-varying magnetic field inside the generator creates an electric field via electromagnetic induction, which creates a voltage difference between the generator terminals.
What causes back EMF?
When the coil of a motor is turned, magnetic flux changes, and an emf (consistent with Faraday's law of induction) is induced. The motor thus acts as a generator whenever its coil rotates. ... The back emf is represented as a variable emf that opposes the one driving the motor.
How do I create an EMF file?
- Type ExportEMF.
- In the dialog box, specify the following: Save in: Navigate to the folder where you want to store the file. File name: Type a name for the file.
- Click Save.
What program opens EMF?
Image-editing applications such as Microsoft OneNote 2010 and IrfanView open EMF files, as can Microsoft Paint and Windows Photo Viewer, which are native to Windows 7.
How do I save a Word document as an EMF?
Click the save as icon in the Option Settings dialog box to open the Save As dialog box>select the directory for exporting the file converted from Word to EMF.> Name the EMF file>Specify the file type as EMF File “*. EMF” on the drop-down menu of Save as type from the combo box.>Oct 20, 2011
What is an EMF file used for?
EMF, acronym of “Enhanced MetaFile” is an image format most used in Windows OS for printing purposes. ... EMF files are most used as cached data for printing. More specifically, When a user commands a document to be printed while already a printing is going on, the later document is saved as EMF file.
Do generators create emf?
Electric generators induce an emf by rotating a coil in a magnetic field, as briefly discussed in Induced Emf and Magnetic Flux.
Do generators emit radiation?
Generating, transmitting, distributing, and using electricity all expose people to ELF radiation. Power lines, household wiring, and any device that uses electricity can generate ELF radiation.Apr 18, 2017
Is there back EMF in generator?
Back emf is the generator output of a motor, and so it is proportional to the motor's angular velocity ω. It is zero when the motor is first turned on, meaning that the coil receives the full driving voltage and the motor draws maximum current when it is on but not turning.
What is back emf and what is its significance?
The significance of Back EMF Back emf is very significant in the working of a dc motor. The presence of back emf makes the d.c. motord.c. motorEfficiency for a BLDC motor of up to 96.5% have been reported, whereas DC motors with brushgear are typically 75–80% efficient.https://en.wikipedia.org › wiki › Electric_motorElectric motor - Wikipedia a self-regulating machine i.e., it makes the motor to draw as much armature current as is just sufficient to develop the torque required by the load.
What is back emf class 12?
CBSE NCERT Notes Class 12 Physics Electromagnetic Induction. Self-induced Emf is also known as back Emf. Back Emf tries to oppose change in the current.It tries to bring back the current. ... In a coil there is increase in the current as a result there is change in the magnetic flux because of that there is induced Emf.
What is back emf how it is generated where it is generated?
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.