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5K40.72 - Back EMF

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​5K40.72 - Back EMF

Preview
SelectSelected
Title5K40.72 - Back EMF
Objective

Demonstrate back emf in a motor.

StatusAvailable
Assembly Instructions

Instructions
The large DC motor with its starter box is connected as shown to the DC supply with the 5-A projection meter connected in series. The motor is started by slowly moving the arm on the starter box up to the stop. Running with no load, the motor will draw about two amps, but if it is braked with a block of wood to produce a load, the current will go up to six amps or more, showing that the back emf has decreased. The effect of the back emf can also be shown by pushing the starter arm up and holding it; the current will drop as the motor gains speed.

Setup Time20
Operation Time
Preview Time5
Operation Instructions
ExportableNo
Demo on DimeNo
PIRA 200No
Export Instructions (if different)
HazardsNone
Analysis/Information
Category5 Electricity and Magnetism
Subcategory5K - Electromagnetic Induction
Keywordsinduced emf, electromotive force
Construction Information
 
  
  
large DC motor
1
starter box
1
ammeter projection - 0-15A
1
power supply - high voltage, DC
1
block - wood
1
banana cable
4
camera - b&w
1
squeezee clamp
2