Science
Why Does Static Electricity Give You a Shock?
Contact and separation between materials can leave charge on your body. Near metal, a brief discharge crosses air and skin to reduce the potential difference, stimulating sensory nerves.
SCIENCE
Science
The principles and discoveries behind the phenomena all around us.Science
How Does Salt Melt Ice?
Salt dissolves in a thin water film and lowers its freezing point. Ice then melts when conditions are above the new freezing point, although the effect has low-temperature limits.
Science
Why Does Metal Feel Colder Than Wood?
Metal and wood may share the same temperature, but metal carries heat away from your hand faster. Rapid skin cooling makes it feel colder.
Science
Why Is the Sky Blue?
Air molecules scatter shorter wavelengths of sunlight more strongly. Blue light redirected toward us from across the atmosphere makes the daytime sky appear blue.
Science
How Does Soap Remove Grease?
A soap molecule grips oil at one end and interacts with water at the other. Groups of them surround grease in micelles that rinsing water can carry away.
Science
Why Does Ice Float on Water?
When water freezes, its molecules form an open crystal structure and expand by roughly 9 percent. The resulting lower density keeps ice afloat.
Science
A Puffy Cumulus Cloud Can Hold About 500 Tonnes of Water
In a standard example, the tiny droplets spread through a cumulus cloud add up to about 500 tonnes of water. A simple calculation explains the estimate—and why the cloud still floats.
Science
A Rainbow Is Actually a Full Circle
Rainbows are circular optical phenomena, but the horizon usually hides the lower half from observers on the ground.
Science
Even a Single Banana Contains Radiation
Bananas contain trace amounts of radioactive potassium, which scientists sometimes use as a fun reference unit called the "banana equivalent dose."
Science
The Food That Never Spoils: The Secret of Honey
Honey jars found in ancient Egyptian tombs were still perfectly preserved after 3,000 years — here's the science behind why honey never goes bad.
