Squeeze It, Shock It

In 1880, Jacques and Pierre Curie discovered something strange: squeeze certain crystals and they produce voltage. This is the piezoelectric effect — mechanical pressure turned straight into electricity. The name comes from the Greek piezo, "to press."

Piezoelectric materials show up everywhere:

• Lighters: click the button, a crystal gets struck, and the voltage makes a spark
• Quartz watches: electricity makes the crystal vibrate exactly 32,768 times per second
• Ultrasound machines: crystals turn electricity into sound waves and back
• Inkjet printers: voltage flexes a crystal that flicks each ink droplet onto the page.