Energy Routes at the Mountain Footbridge

Tests on the Bridge Landing

At a mountain footbridge, a trail crew set up a worktable on a wide landing away from passing hikers. They wanted to compare ways to move energy between two places. An adult checked the equipment. The crew tested a chime, a flashlight and mirror, warming strips, and a battery-powered lamp. They recorded what happened instead of judging a design by its appearance.

For the sound test, Amira stood three meters from the chime. Dev tapped it once. Amira heard the ringing. The crew placed a large, solid board between the chime and Amira. She could no longer see the chime, but she still heard it. They kept her distance and the chime's position the same.

For the light test, Dev aimed a flashlight at a small mirror. A bright patch appeared on a white card to the side of the flashlight. Turning the mirror moved the patch off the card. The crew returned the mirror to its first position. They then put the solid board between the flashlight and mirror. The patch disappeared. They removed the board, and the patch returned.

For the warming test, the crew used one metal strip and one cork strip with matching lengths, widths, and thicknesses. Both started at 20°C. An adult placed identical sealed pouches of warm water on one end of each strip. Each pouch had the same amount of water at the same starting temperature. The crew measured the temperature at the uncovered far end of each strip after four minutes. The graph shows their results.

For the electric-current test, an adult connected a low-voltage battery pack to a small lamp using two wires. With both wires connected, the lamp shone. When the adult disconnected one wire, the lamp went dark. Reconnecting that wire made it shine again. Finally, the adult hid the battery pack and wires under an opaque cover without changing the connections. The lamp stayed lit.