PUBLISHED : Wednesday, 18 November, 2009, 12:00am
UPDATED : Wednesday, 18 November, 2009, 12:00am

Bolts of lightning

Everyone has seen a thunderstorm. Thunder rolls in the sky and bolts of lightning light it up. The lightning that strikes the ground is electricity. It looks very impressive. But, actually, most bolts of lightning don't have a lot of electrical power.

The average electricity bolt would probably have enough energy to provide power for a Hong Kong apartment for around one month.

People wondered what lightning was since the beginning of history. In fact, we're still not completely sure how it happens. But in 1752, an American called Benjamin Franklin did a test using a kite. He attached a key to the string at the end of the kite during a storm to show that lightning was static electricity. He went on to invent the lightning rod which protects a building from lightning.

The invention that changed the world

Imagine a world with no electricity. We would have to read using candles at night. There would be no television, no cinemas, no air conditioning, no electric fans, no iPods and no internet. That was how people lived until we learned how to use electricity.

The main breakthroughs that created the electrical era did not really happen until about 200 years ago. In 1800, Alessandro Volta invented the first electric battery (electric 'volt' is named after him). In the 1820s, scientists discovered magnets and electricity were related. In 1821, somebody discovered how to make an electric motor. After this, many things began to happen. In 1876, Alexander Graham Bell invented the telephone. In 1879, Thomas Edison finally perfected the electric light bulb.

Turn on the lights

Edison's first light bulbs only burned for about 40 hours. A year later, light bulbs had been developed that could burn for 1,200 hours. Humans were finally about to defeat darkness with something other than fire.

By this time, electricity had begun to bring about the modern world. Electric street cars were invented in 1881. The next year, the first power station in the world opened. It was in New York. It powered around 5,000 street lights. Over the next decade, people worked out how to make power from windmills and from waterfalls - hydroelectric power.

Power for all

In At the beginning, electricity was used for public lamps and trams. It took some time before people had electricity in their homes. For example, in 1942 only half of America's farms had electricity. But that was still a big improvement on 10 years earlier. At that time only 11 per cent had electricity.

now do this

1 The average bolt of electricity could power a Hong Kong apartment for ...

a. one day

b. one month

c. three years

2 The first electric power station opened in ...

a. London

b. Boston

c. New York

3 The electric light bulb was perfected by ...

a. Thomas Edison

b. Graham Bell

c. Alessandro Volta


November 11

1. b, 2. b, 3. a