Beyond the answers - interesting background to this quiz

A river that feeds hundreds of millions

The Ganges rises in the western Himalayas and flows southeast across the plains of northern India before emptying into the Bay of Bengal. Along the way it passes through cities such as Varanasi and Patna, and it is joined by major tributaries including the Yamuna. For Hindus the river is sacred, and its waters are used in rituals of purification. It is also a working river, supporting farming and fishing for a vast population.

Franklin's kite and the language of charge

Benjamin Franklin's famous kite experiment in 1752 was designed to show that lightning is electrical in nature. Franklin also helped establish the convention of describing charge as positive and negative, the same vocabulary we still use in physics lessons today. It is worth noting that the choice of which charge to call "positive" was arbitrary, and later discoveries about electrons did not change the labels.

Malta's money and its place in Europe

Malta is a small island country in the Mediterranean, south of Sicily. It adopted the euro in 2008, a few years after joining the European Union in 2004. Before that, its currency was the Maltese lira, which had replaced the pound. Malta is one of the smallest eurozone members by population, yet it uses the same banknotes and coins as much larger economies such as Germany and France.

The boomerang: more than a returning toy

The boomerang is most closely associated with Aboriginal Australian cultures, where it has been used for thousands of years. Traditional boomerangs are carved from wood, often from species with naturally curved branches or roots. Not all of them return: many are heavy hunting tools designed to travel in a straight line. The returning type is a lighter, more specialised shape, and it is the one most people picture today.

Ravel's Bolero and a career of precision

Maurice Ravel composed Bolero in 1928, and it remains his most famous work. The piece is built on a single rhythmic figure that repeats from start to finish while the melody is passed around the orchestra and the volume gradually grows. Ravel was a meticulous craftsman, and his other works include the piano suite Miroirs and the ballet Daphnis et Chloe.