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

# Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography

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.

 Choose a Topic or Enter a keyword to search: I cannot find what I want! You have selected the following Demos: None Selected

Choose a subtopic:
Electrostatics
Electric Fields And Potential
Capacitance
Current and Resistance
Electromotive Force And Current
DC Circuits
Magnetic Materials
Barkhausen Effect
Electromagnet
Diamagnetic Levitation
video  - Hysteresis
Curie Point
Meissner Effect (diamagnetic levitation)
Magnetism
Inductance
Induction
Complex Circuits
Semiconductors And Tubes
Transmission Lines and Antennas

### Electromagnet

#### Purpose:

To demonstrate electromagnetism.

#### Procedure:

The battery magnet has a very smooth surface and once energized is extremely hard to pull apart. If challenged, students will try in vain to seperate the two pieces.

The electromagnet is wound with four 0.0135" diameter copper wires in parallel. The length of each wire is from back edge of Rm. 203 big bench to last step just outside back door. The resistance of each wire is about 4.5Ω. If the magnet seems weaker than normal, it is possible either the battery is low or one of the wires is broken.

#### Hints:

Note: We measured the impedance, inductance and current draw for this electromagnet assuming a 9V battery that has about 8-9V starting voltage.
• Z = 6 Ω
• L = 2 mH
• I = 1 A

#### Equipment:

• 9 V battery pack