1 / 7

# Meters and Motors - PowerPoint PPT Presentation

Meters and Motors. Principles of Physics. F. S. N. F. e -. A wire loop placed in a uniform magnetic field experiences a turning force The loop only rotates 90˚, then stops. dial. spring. F. S. N. F. e -. Galvanometers.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Meters and Motors' - benny

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### Meters and Motors

Principles of Physics

S

N

F

e-

• A wire loop placed in a uniform magnetic field experiences a turning force

• The loop only rotates 90˚, then stops

spring

F

S

N

F

e-

Galvanometers

• measure weak electric currents, and thus measure magnetic fields

• made by placing a wire loop in a magnetic field

• a needle and a spring are attached to the loop

• the needle rotates with the loop to indicate the current value

• the spring allows the needle to return to its initial position after the current is removed

Ammeters

• measure larger currents

• made by adding a low resistance shunt in parallel with a galvanometer

• Most of the current flows through the shunt. The needle moves less, to measure bigger currents

• Lower the shunt’s resistance, bigger current it can measure

Voltmeters

• measure voltage

• Voltmeters are added in parallel because their high resistance keeps current from being diverted through the meter

• A motor converts electrical energy into mechanical energy

• An iron core is attached to a shaft that allows it to spin

• A coil is wrapped around the iron core to concentrate the magnetic field and increase the turning force

• Split ring commutators reverse the current after each ½ rotation so it continues to spin in the same direction

• Brushes are wires that brush against the stationary contacts on the shaft