Ring and Ball

The metal objects become extremely hot and remain hot for several minutes after heating. Use heat-resistant gloves or tongs. Keep flammable materials clear. Ensure the torch is completely off before setting it down.

Never pass hot objects to students. Have a beaker of water available for cooling between successive demonstrations.

Purpose

A brass ball that just fits through a brass ring no longer passes through when the ball is heated, but does pass when the ring is also heated. Directly addresses the common misconception that holes shrink when heated — they expand just like the surrounding material.

Handheld ring-and-ball apparatus: two brass balls on rods with black handles and a brass ring on a wooden handle (Gravesande's ring and ball)

Figure 1:

Propane Torch

1

Short Ring and Ball

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Warning: Heat and Fire Hazard

Warning: Burn Prevention

Purpose

Safety Warnings

Warning: Heat and Fire Hazard

Warning: Burn Prevention

Purpose