Complete the sentences with the correct form of the present perfect or past simple.
1) Success of the Yablochkov candle in 1878 ________(exceed) all expectations – mass media all around the world ____(write) about the outstanding invention of a Russian scientist.
2) Electricity ______(be) a subject of scientific interest since at least the seventeenth century.
3) In the 19th century the subject of electrical engineering with tools of modern research techniques,
__________(start) to intensify.
4) Electricity is used with telecommunications, and indeed the electrical telegraph, demonstrated in 1837 by Cooke and Wheatstone _____(be) one of its earliest applications.
6) Electricity is the best source of energy. While there are other sources of energy none of them
__________(reach) the stage where they can be used to provide the power to help modern life go.
6) The processes used to produce electricity using the sun’s energy historically ________(be) more expensive than using conventional fossil fuels.
7) In 2015, less than 1% of the nation’s electricity __________(supply) by solar power.
8) In 1827 Georg Simon Ohm _________ (quantify) the relation between electrical current and potential difference between conductors – leading to Ohm’s law.