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Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography

PLEASE REQUEST DEMOS WELL IN ADVANCE

Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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 Electrostatics
 Electric Fields And Potential
 Capacitance
 Current and Resistance
 Electromotive Force And Current
 DC Circuits
 Ohm's Law
 Resistivity of a Pencil
 Resistive Heating of Nichrome Wire
 Blowing a Fuse
 Wheatstone Bridge
  video  - Wheatstone Bridge II
  video  - Circuit Analysis
  video  - RC Circuit w/ Function Generator
 RC Circuit w/ Battery
 RC Time Constant (DECAY)
 Telephone model as simple DC circuit
 Magnetic Materials
 Magnetism
 Inductance
 Induction
 Complex Circuits
 Semiconductors And Tubes
 Transmission Lines and Antennas

 video  - Circuit Analysis

Purpose:

Simulation of how a house would be wired with 120VAC, the circuit analysis board is an introduction to simple series and parallel resistive circuits using light bulbs.

Procedure:

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  DEMO VIDEO DOWNLOAD w/ sound / 1920x1080 / 24.19Mb/s / 473MB size  


  DEMO VIDEO DOWNLOAD w/ sound / 854x480 / 5.69Mb/s / 113MB size  


The apparatus consists of an AC circuit board with five E26 medium screw light sockets. Two shorting plugs, 25W bulbs and 60W bulbs are provided. The wiring schematic is shown on the board by strips of black tape. Bulbs can be arranged is series, parallel or combinations. Bulbs are not ideal resistors, but qualitative results can be achieved which can help students to understand current flow in simple circuits. For example:
  • The reason houses are wired in parallel rather than series can be illustrated by successively adding same power rated bulbs to the board first in series and then in parallel.
  • Using a 25W and a 60W bulb, ask students which will be brighter when they are wired in series and then in parallel. Why?
  • More complicated circuits can be wired, but make sure to try them out ahead of time, it is easy to get confused when doing things "off the cuff"!

Hints:

The lower a bulb's power rating, the higher its resistance. Given the same voltage, a 60W bulb will shine brighter than a 25W bulb.
  • use 25W and 60W light bulbs
  • use shorting plugs
  • use a power strip for easy power ON/OFF

Equipment:

  • Outlet Strip
  • Circuit Analysis Board