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                BCIT Physics Department

Demonstration Manual

Electricity and Magnetism

DEM20.1 - Temperature Coefficient of Resistance (Method II)

Objective:

- To model the movement of electrons through a conductor and the effect of temperature on the resistance of a conductor.

Electrons are modeled using steel balls, the conductor is modeled using a grid of nails, voltage is modeled by sloping the grid and temperature is modeled by causing the grid of nails to vibrate along an axis perpendicular to the slope.

Apparatus:


DEM20.1 - Temperature Coefficient of Resistance (Method II)

Method:

Amplifier settings:

Wave generator settings:

Set up the apparatus and controls as shown above. The nail grid should be leveled along the axis of vibration, and have a slope of 5-10 with respect to the horizontal, along its length.

Place all five 3/4" steel balls into the top of the grid at the same time, and measure the time required for 3 balls to reach the bottom (median time for 5 balls to reach bottom).

Turn the power ON for the amplifier first and then the wave generator. Turn the volume control of the amplifier to 3. The grid should vibrate at 15Hz. Place all five 3/4" balls into the top of the grid at the same time, and again measure the time required for 3 balls to reach the bottom.

It should take longer for the balls to pass through the grid when it is vibrating than when it is stationary.

Try varying the slope, amplitude, ball size and/or frequency and observe the results.