Energy Clues at the Tent Door

Four Tests at Camp

During a camping trip, Nia and Arun set up four tests near their tent after sunset. An adult checked the equipment and helped record observations. They used a small speaker, a flashlight, water containers, and a low-voltage battery-and-lamp kit. They did not use a campfire or plug anything into a wall outlet. Before each test, they checked that nearby equipment was switched off.

For the sound test, Nia placed the speaker inside the tent. Arun stood outside, two meters from it. The speaker played a quiet tune. Arun heard the tune with the tent door open. He also heard it after Nia zipped the door shut. When Nia switched off the speaker, Arun no longer heard the tune. They kept the speaker volume and Arun's distance the same.

For the light test, they aimed a flashlight at a white card one meter away. A bright spot appeared on the card. They held a clear plastic sheet across the beam, and the spot remained. Next, they replaced the clear sheet with thick cardboard. The spot disappeared. When they removed the cardboard, the spot returned. The flashlight stayed on and pointed in the same direction throughout these steps.

For the water test, an adult placed a thin plastic cup of water in a shallow basin of warm water. The cup water started at 20°C, matching the air temperature. The adult kept the basin water near 40°C. The cup's rim stayed above the basin water, so the waters did not mix. They left the same cup and amount of water in place and measured its temperature over ten minutes. Their results are graphed below.

Finally, they connected a battery to a small lamp using wires and a switch. The battery was one meter from the lamp. With every connection secure and the switch closed, the lamp lit. Opening the switch made the lamp go dark. Closing it again made the lamp light. The battery, lamp, and wires stayed in the same places.