Category Archives: Electromagnetic Inductions

Shaded-Pole Motor

Demo: EM-K-SP
Pira Index:  5K 20.50

 Lab Equipment  Directions
  1.  Electromagnetic solenoid
  2. Variac
  3. Copper plate and large copper sphere with black stripe
  4. 1000 ml beaker with 1 drop of liquid soap and to float the sphere
  1.  Remove the PVC rod if it is under the coil to allow iron core to drop with the top of the solenoid coil.
  2. Place the plate over the core lining up the markings on each to make a complete circle.
  3. Place the beaker containing water, soap, and ball on the center of the solenoid.
  4. Adjust the variac until ball spins. Minor adjustments may be made in the placement of the plate to insure optimal spin.


Special Faraday Setup

Demo: EM-K-SF
Pira Index: 5K 10.00

 Lab Equipment  Directions
  1.  Large magnet
  2. Demo galvanometer
  3. Jumping ring coil and aluminum rings
  4. HBS power supply
  5. Black coil on spool
  6. Yellow coil and long AA coil
  7. Wood handle magnet
  8. Variac
  9. Hand generator
  10. Lenz’s law tubes
  11. 2 BB leads
  1.  Set up as shown.
  2. Show the effect on galvanometer of moving a coil through a magnetic field or vice versa.
  3. Show the effect of a magnetic field on aluminum rings within the field.
  4. Show the production of electricity with a hand-driven generator.
  5. Show eddy currents in Lenz’s law tube.



Ring Toss

Demo: EM-K-RT
Pira Index: 5K 20.30

 Lab Equipment  Directions
  1.  Electromagnetic solenoid with PVC pipe
  2. 3 metal rings (cooper, aluminum, and split-ring aluminum)
  3. Foot switch
  4. Variac
  1.  Plug foot switch into variac and plug solenoid into back of foot switch plug. Turn variac on and turn power to maximum.
  2. Place the copper ring over the iron core, tap the foot switch momentarily and watch the ring jump. Tapping foot switch and releasing will prevent high voltage use longer than 1 second.
  3. Repeat with unsplit aluminum ring.
  4. Repeat again with split aluminum ring.
  5. Remove split ring and place a solid ring back on iron core. Adjust variac to about 70v then hold ring down while power is turned on. The ring will begin to heat.


RL Circuit AC/DC

Demo: EM-K-RL
Pira Index: 5K 00.00

 Lab Equipment  Directions
  1.  Coil with removable core
  2. 12v transformer (dark gray)
  3. Special base with 6v bulb in silver screw base adaptor
  4. HBS power supply
  5. 3 BB leads (long)
  6. 5 or 6 paper clips
  1.  Connect transformer, bulb, and coil in a series circuit as shown.
  2. Slowly insert the core into the coil and watch the bulb dim.
  3. Remove the core. Remove the leads from the transformer and connect them to the power supply. Slowly increase the voltage.
  4. Insert the core. Note that the bulb does not dim. Place paper clips near the end of the core.




LED Turn by Turn

Demo: EM-K-LT
Pira Index: 5K 10.00

 Lab Equipment  Directions
  1.  Electromagnetic solenoid with core extended
  2. Variac
  3. 3 wire coils with LED’s attached
  1.  Plug the electromagnet into the variac.
  2. Slide the LED attached to 7 turns of wire over the core. Turn on the variac and slowly increase the voltage until the LED just starts to glow.
  3. Leaving the 7 turns on the core, slide the 9 turn LED over the core, followed by the 11 turn coil. Notice the increasing brightness with each increase in the number of wires.


Lenz’ Law Rod

Demo: EM-K-LR
Pira Index: 5K 20.25

 Lab Equipment  Directions
  1.  Lenz’s law rod
  1.  Hold the rod vertically and watch the copper ring slide down the length of the tube, noting changes in the rate at which the ring falls.
  2. Turn the rod over and again observe changes in the rate of fall of the copper ring.
  3. Ask students to figure out what is happening.

(On one end of the rod the silver magnets are aligned N to S, and the other end N to N and S to S)

Lenz’s Law Plates

Demo: EM-K-LP
Pira Index: 5K 20.25

 Lab Equipment  Directions
  1.  Lenz’ plate apparatus
  2. One solid aluminum plate
  3. One notched aluminum plate
  1.  Drop the solid plate down the side without the attached magnets.
  2. Drop the solid plate down the side with attached magnets. Note the difference in fall time.
  3. Drop the notched plate down the side with the magnets. Note the difference in the fall time between the solid and notched plates.