Beyond the answers - interesting background to this quiz

A continent of fifty-four voices

Africa's 54 countries make it the continent with the largest number of sovereign states, and that figure is not fixed in stone. South Sudan became the newest member in 2011 after gaining independence, while unresolved questions over Western Sahara mean the count can be debated depending on who is doing the counting. The continent also holds the largest number of member states in the African Union.

Moscow's many layers

Moscow has served as Russia's capital for centuries, though it briefly lost that role. In 1712 Peter the Great moved the seat of government to the new city of St. Petersburg, which remained the capital for more than two hundred years until the Bolsheviks shifted it back to Moscow in 1918. Today Moscow is one of Europe's largest cities by population.

Where the Equator actually runs

The Equator crosses thirteen countries in total, spread across Africa, South America and island nations in the Pacific. Congo, in Central Africa, is one of them, and the line passes through some of the world's densest rainforest. Curiously, Italy and Egypt sit well outside the tropics, so neither comes close to the Equator.

Watt and the engine that powered an era

James Watt did not invent the steam engine, but his improvements in the late 18th century made it dramatically more efficient. By adding a separate condenser, he prevented the main cylinder from constantly losing heat. This refinement helped steam power move from pumping water out of mines to driving factories, a key step in the Industrial Revolution. The unit of power known as the watt is named in his honour.

Measuring electricity, one unit at a time

Electric charge is measured in coulombs, named after the French physicist Charles-Augustin de Coulomb. It is easy to confuse with the ampere, which measures electric current, or the ohm, which describes resistance. In simple terms, one ampere is one coulomb of charge flowing past a point each second, which is why the two units often appear together.