Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)

“The Tonight Show” host Jimmy Fallon, center, exits the water during the Chicago Polar Plunge, Sunday, March 2, 2014, in Chicago. Fallon joined Chicago Mayor Rahm Emanuel in the event. (Photo by Andrew A. Nelles/AP Photo)

A Lebanese man carries an injured woman away from the site of a car bomb explosion in a Shiite area and stronghold of the Lebanese militant group Hezbollah at the southern suburb of Beirut, Thursday January 2, 2014. A large explosion has rocked a stronghold of the Shiite Hezbollah group in the southern suburbs of the Lebanese capital. (Photo by Hussein Malla/AP Photo)

Barrier tape is tied around 15-month-old Shivani's ankle to prevent her from running away, while her mother Sarta Kalara works at a construction site nearby, in Ahmedabad, India, April 19, 2016. Kalara says she has no option but to tether her daughter Shivani to a stone despite her crying, while she and her husband work for 250 rupees ($3.8) each a shift digging holes for electricity cables in the city of Ahmedabad. (Photo by Amit Dave/Reuters)

A woman takes a selfie in front a damaged Turkish military APC that was attacked by protesters near the Turkish military headquarters in Ankara, Turkey, Saturday, July 16, 2016. (Photo by Hussein Malla/AP Photo)

Supporters of U.S. Democratic presidential nominee Hillary Clinton react at her election night rally in Manhattan, New York, U.S., November 8, 2016. (Photo by Lucas Jackson/Reuters)

Young U.S. visitors pose for a photograph next to a vintage car in Havana March 16, 2016. (Photo by Ueslei Marcelino/Reuters)

Women wearing traditional dresses with pins of pictures of former North Korean leaders Kim Il Sung and Kim Jong Il welcome foreign reporters on a government organised visit to the Kim Jong Suk Pyongyang textile mill in Pyongyang, North Korea May 9, 2016. (Photo by Damir Sagolj/Reuters)