Save guides, add subjects and pick up where you left off with your BBC account. Waves transfer energy from one place to another. Light from the Sun travels through space and through the atmosphere ...

The threat of load shedding looms over the collective head of South Africa and rumours, facts and some hysteria swirl around much like pure sine waves ... DC and stores the energy into battery ...

Among other things, the rising tensions between the two countries have rattled the international energy market, as Russia is a huge energy producer and exporter, and a large percentage of Russian oil ...