P
E
The invention of
the light bulb
Read the text on the invention of the light bulb and fill in the gaps in the text on the
worksheet
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The parts of a light bulb
P
Fill in the gaps in the text on the worksheet „The parts of a light bulb“ using these
words:
- base contact - thread – glas bulb - coil fixing wire – insulation body -
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The energy saving bulb
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1. Find out what an energy saving lamp consists of and how it works.
2. Use the following words to fill the gaps on the worksheet.
- electronic transformer – base switch - coil - glass tube – phosphor film – mercury steam 3. Answer the questions on the worksheet.
H
Material:
- cable
- plug
- tools
W
Extension cable
wire insulation
cable cover
wire
Tasks:
1. Make an extension cable and show it to me so that I can check it.
2. After this draw
a) a cross section of the plug
b) a cross section of the cable with the correct colours.
3. Label the parts.
Safety plug
There are two metal contacts in safety sockets, the safety contacts. They are
connected to the green and yellow cable, the earth wire. In a dangerous situation the
earth wire diverts the electricity and causes a short circuit of the fuse.
Take note of the following:
- The wires which conduct the electricity are brown (black) and blue and the earth
wire is green and yellow.
- The braids at the ends of the wires are secured with press sleeves. The screws on the
sleeves must be tight, so that a safe contact is ensured. A loose contact can cause
sparks to fly and can cause a cable fire.
- The yellow and green earth wire must be longer than the other two. To do this you
lay it in a loop inside the plug. Should the cable be pulled out of the plug this ensures
that the conducting wires will come out first before the earth wire comes out.
- The cable is additionally secured to the casing with a bridge. If the cable is pulled
the bridge offers additional support.
bridge
loop
safety contacts
earth wire
The invention of the light bulb
The German-American ____________________________ was
the first person to concern himself with the electric
________________________. He pumped the air out of
the___________________ and using electricity made a
___________________ thread glow brightly. However the
inventor of the first real light bulb was __________
__________________. In his laboratory in Menlo Park near
___________________ he first tried to use filaments made of
carbonized ________________________.
____________________ was particularly suitable. After more
than a year of experimenting he finally succeeded in making a
light bulb _________________. It burned for _____ hours. His
next bulb with a filament of carbonized _________________. It
burned for 170 hours.
Edison’s ________________________ had a great advantage over
all the earlier attempts at making bulbs: Its filament was as thin as
a____________________ and therefore needed only a very
small______________.
Around 1900 the bulbs with carbonized filaments were replaced
by _______________ . In the meantime it had been possible to
produce a durable filament from the hard and rigid
_______________metal.
Today ____billions of light bulbs are produced all over the world,
of which ___________ billions are ______________.
If all the bulbs produced in a year were laid down end to end how
many times would they fit round the earth?(a bulb is an average of
10 cm in length) ________________
The parts of a light bulb
1. Label the parts of the light bulb and colour the conducting parts red.
2. Colour the electrical circuit red.
The energy saving bulb
The energy saving lamp consists of two parts: a phosphorescent tube and
an electronic transformer.
The phosphorescent tube consists of glass. On the inside
the glass tube has a thin layer of phosphorescent material.
This is why it looks white. There is mercury steam and
small amounts of noble gases inside the tube.
electronic
transformer
But the phosphorescent material will not light up on its
own. And you will want to be able to switch the lamp off.
This is why we need the transformer. In principle it
produces only a single current, that is electrons (small
negatively charged particles). The electrons “fly” through
the mercury steam. When they collide with a mercury
particle a streak of UV light is produced. UV light
(ultraviolett light) cannot be detected by the human eye.
However when the streaks of UV light hit the layer of
phosphor they are transformed into visible light.
Since the energy saving bulb does not have a filament to
produce light like a normal light bulb it does not become so hot. A normal
light bulb also produces heat and therefore requires a lot of energy.
The energy saving bulb
1. Where is the electricity which flows through the mercury steam
produced? ________________________________________________
2. Explain how light is produced in the mercury steam.
____________________________________________________________
____________________________________________________________
____________________________________________________________
3. What is the purpose of the layer of phosphor?
____________________________________________________________
____________________________________________________________
4. Why should broken energy saving bulbs not be put into the normal
household rubbish?
___________________________________________________
____________________________________________________________
5. Why does an energy saving bulb use less energy than a normal light
bulb? _________________________________________________
____________________________________________________________
____________________________________________________________