The end of the light bulb.
Over a hundred years since Edison invented it, the traditional light bulb will soon be gone forever. That's the official decision in Europe at least. So, what's wrong with this invention?
The light bulb works on a simple principle. When a current is sent along a thin piece of wire, the wire gets hot. If the wire is thin enough and the current is high enough, the wire will start to glow and create a lot of light. Normally this would then make the wire burn out. You might see this in a physics class. On the other hand, if the metal is strong enough and it is in a special atmosphere, it will survive for longer and not burn away. A traditional bulb, called an incandescent light bulb, uses a very thin piece of tungsten in an atmosphere of argon and nitrogen. Tungsten can survive at extremely high temperatures without melting, and without oxygen nothing can burn anyway. Eventually, oxygen leaks in from the earth's atmosphere or the tungsten wire (called a filament) breaks and it is time to buy a new bulb.
The new type works a different way. It uses a tube of gas (a different type) which conducts electricity. This sort of gas gives off light when a current passes through it, but produces less heat. An incandescent bulb is very inefficient, as only about two or three percent of the electricity is turned into light and the rest is heat. Modern bulbs are far better because they work in such a different way. In fact, they work the same way as the strip lights you often see in all sorts of buildings.
So why don't we all change our light bulbs anyway, European law or not? Well, it's not that simple (these things usually aren't). Firstly, the old style light bulb is extremely cheap. It is, after all, just a coil of wire in a glass bubble. The modern design is more complicated. The materials to make it are more expensive and the technology to build them is also. Look in a supermarket at the two types side by side and you will see the difference in price.
Secondly, as the new design needs a thin tube rather than a balloon of glass, the shape is not exactly the same. Some lights need the smaller type of bulb and don't have enough space for the slightly longer design of the energy-efficient ones.
Finally, although it doesn't make that much difference most of the time, the new ones don't give off quite as much light as the old ones. They also take a couple of minutes to reach their full level of brightness (try it and you'll see). Some people are not happy about this, as they would prefer the replacement to be identical in all ways. However, the person who pays the electricity bill is usually very pleased when they see how much money they have saved.
So there you have it. The invention that has been in everyone's home for over a century is finally retiring. Perhaps in a generation from now you will only see a traditional light bulb in a museum.
Questions
1) Why does the wire in a light bulb get hot?
a – Because it reacts with the atmosphere.
b – Because it is made of tungsten.
c – Because it is so thin.
d – Because the bulb leaks.
2) Why are the new bulbs more expensive?
a – Because they use a different type of metal for the filament.
b – Because they need three percent more material than an incandescent bulb.
c – Because they can't be found in supermarkets.
d – Because they are more complicated to make.
3) What is one of the problems of the new bulbs?
a – They don't produce as much light as the old ones.
b – They don't switch on instantly.
c – They use too much electricity.
d – They don't last as long as the old ones.
KEY
1c 2d 3a
These items are all found in various homes. They all run on electricity. Some are more energy efficient than others.
E N R P V Z R D K B K M F W L
G L C E X W S B M F L O V A G
O B E Z Y B V E A D J A L S R
W T G C D R E F E T C P K H E
J A G F T Z D E V U K O H I H
N S R Y R R R E U E D K Y N S
P E O X O E I M L X P L L G A
F M U O T P C C D B O C P M W
N H P S I L B Y B F M A K A H
V B A H E K T S F L G U M C S
A O A A Y H G S A W A J T H I
T D N I O N I S E R N N K I D
T E F D F S O R B W C W K N G
R O T A R E G I R F E R L E G
C S R A W K S Q C Z U G T O T
KEY
toaster
vacuum cleaner
tumble dryer
washing machine
dishwasher
electric blanket
ioniser
refrigerator