Transcript Lesson 6 DC Motors

ES Lesson 6
• Let’s make a DC motor and learn
how it works.
© 2012 C. Rightmyer, Licensed under The MIT OSI License, 20 July 2012
Recall ES demo 5-10. A compass acting like a DC motor
+
9 volts
A stronger magnetic field is generated when
the wire is formed into a coil
+
+
Electromagnetic field
induced by current
Magnetic field adds in
center of circular coil
L (in microHenrys) = (approximately)
D^2 x N^2 / [(18xD) + (40xW)]
Adapted from Make: Electronics, O’reilly [Publishing], Charles Platt, 2009
Compressing the coil generates a magnetic field
much like a button magnet.
[Intro to College Physics, Appleton-Century-Crofts, R.D. Rusk, 1960]
Torque occurs when magnetic fields intersect
[Intro to College Physics, Appleton-Century-Crofts, R.D. Rusk, 1960]
A DC motor needs commutator slip rings
BATTERY
[Intro to College Physics, Appleton-Century-Crofts, R.D. Rusk, 1960]
How a DC motor works
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html
ES project 6-1. Make a working DC motor
BE demo 1-13
1 ½ inch
(1) Prepare the stantions. Use needle nose pliers
to shape a spiral hook 1½ times around each end
of 6” length of straight 20 gauge copper wire.
(2) Insert the stantions in pre-drilled holes so that
the bottom of both hooks are ¾ of an inch
above the platform.
(3) Superglue the stantions in place, and then a 1”
button magnet between them.
Adapted from [Usborne, Electricity and Magnetism, Adamczyk and Law, 1993]
Backup slides
Another fun motor demonstration (Step 1)
https://www.youtube.com/watch?v=J9b0J29OzAU
Another fun motor demonstration (Step 2)
https://www.youtube.com/watch?v=J9b0J29OzAU
Another fun motor demonstration (Step 3)
https://www.youtube.com/watch?v=J9b0J29OzAU