Category Archives: DC Circuits

Series and Parallel Circuits

Demo: EM-F-SP
Pira Index: 5F 20.50

 Lab Equipment  Directions
  1.  Light bulb apparatus A, B, C (in picture)
  2. Variac
  3. Light bulb
  4. Glove – heavy type cloth
*Show that bulbs in series all go out if one is removed, but not so with the bulbs in parallel
*Change the number of bulbs in the circuit-with more bulbs in series they glows more dimly, in parallel they glow brightly
*figure C arrangement shows that high wattage bulbs conduct more current
  1.  Plug circuit as shown in figures A, B, or C into variac.
  2. Loosen bulbs as desired to demonstrate effects of each circuit.
  3. Figure C circuit is more complex. Unscrew the center three bulbs in any combination and watch the brightness change each time.
Warning: Do not touch metal surfaces when the circuit is turned on.


Series Joke Circuit II

Demo: EM-F-SJ
Pira Index: 5F 20.00

 Lab Equipment  Directions
  1.  Series joke circuit (Low Voltage)
  1.  Connect circuit to power. Make sure that both switches are closed.
  2. Open one of the switches and observe. Close the switch again.
  3. Open the other switch and observe.
  4. Now open both switches and observe.



Resistance of a Wire

Demo: EM-F-RW
Pira Index: 5F 20.40

 Lab Equipment  Directions
  1.  Wheatstone apparatus with 2 spade adaptors attached
  2. Fluke 75III multimeter OR large demo multimeter
  3. 2 B-B leads
  1.  Connect as shown.
  2. Use the sliding tap to measure the resistance of various lengths of wire.
Set multimeter on Ω.
The full length of the wire resistance should read approximately 3.3 Ω. Half length ~ 1.6Ω



Ohm’s Law (DC)

Demo: EM-F-OD
Pira Index: 5F 10.10

 Lab Equipment  Directions
  1.  HBS power supply
  2. Demo multimeter
  3. 3 ohmite high-wattage resistors – brown ceramic (2&2 connected, 8 single)
  4. 4 leads: 2 B-B, 2 B-A
  1.  Set up equipment as shown.
  2. For several different settings on the power supply, measure the voltage (on the DMM) and the current (on the power supply).
  3. Using V=IR see if the R calculated from the measurements agree with the given value on each resistor.
(A 2-ohm resistor can be measured or the two 2-ohms measured in series for the 4 ohm)



Hot Dog Cooker

Demo: EM-F-HD
Pira Index: 5F 15.20

 Lab Equipment  Directions
  1.  Hot dog cooking apparatus with 3 leads
  2. 2 LEDs
  3. Special AA shorting lead
  4. Fluke 75III DMM
  5. Variac
  6. 8 hot dogs
  7. Tray
  1.  Place as uncooked hot dog between lower posts as shown. Connect circuit as shown. *Plug apparatus into variac and turn it to 110V.
  2. To cook 2 hot dogs in parallel, connect the AA shorting lead across the 2 posts on the right side.
  3. To cook 2 hot dogs in series, remove the AA shorting lead. Move the ’10A’ lead to series position as indicated in the photo.
CAUTION: DO NOT touch the hot dog or any metal parts while apparatus is plugged in.