Submitted by: Ernest F. Silversmith,' Morgan State College, Baltimore, Md.
Checlced by: D. Michael Barnes, Hiram College, Hiram, Ohio 44234
PREPARATION
Prepare a "shield" by placing a book or board (10 X 14 in. or larger) on four 21/,-in. cubic blocks, one under each corner. Provide l-in. balls, such as styrofoam, wood, or sponge rubber, a square object about 2 X 8 X 8 in., a round object about 2 in. thick and 8 in. in diam., and other suitable objects. DEMONSTRATION
A volunteer is selected from the audience and asked to turn his back to the shield. He is told that the instructor will place a square object, or a round object, or nothing under the shield. The volunteer is then asked to turn around and roll a 1in. ball under the shield as often as he wishes and to infer what is underneath
by observing where the ball emerges. The class and the instructor then discuss the analogy between this demonstration and the Rntherford experiment. REMARKS
The sizes of materials can he increased if the demonstration is given in a large room or they can be scaled down and placed on an overhead projector for a demonstration in which the entire class would be involved in the inference. An ingenious exhibit at Pacific Science Center in Seattle, Washington, suggested tbir audience-participationdemonstration of Rutherford's famous work in which he deduced the existenoe and nature of the nucleus. WISWESSER, W . J., J. CHEM.EDUC., 22,370 (1945). Journal of Chaniool Edueolion
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August 1971
Volume 48, Number 8, August 1971
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A499
