Home' Trinidad and Tobago Guardian : August 10th 2015 Contents Guardian www.guardian.co.tt Monday, August 10, 2015
DIRECTIONS: Read the passage carefully before attempting the questions. Each question has four options, select
the most appropriate answer, based on what is contained or implied in the passage.
HISTORY OF THE LIGHT BULB
The electric light is one of the everyday conveniences that most
affects our lives, was not "invented" in the traditional sense in
1879 by Thomas Alva Edison, although he could be said to have
created the first commercially practical incandescent light. He
was neither the first nor the only person trying to invent an in-
candescent light bulb. In fact, some historians claim there were
over 20 inventors of incandescent lamps prior to Edison's ver-
sion. However, Edison is often credited with the invention be-
cause his version was able to outstrip the earlier versions
because of a combination of three factors: an effective incan-
descent material, a higher vacuum than others were able to
achieve and a high resistance that made power distribution
from a centralized source economically viable.
Early Light Bulbs
In 1802, Humphry Davy invented the first electric light. He ex-
perimented with electricity and invented an electric battery.
When he connected wires to his battery and a piece of carbon,
the carbon glowed, producing light. His invention was known
as the Electric Arc lamp. And while it produced light, it didn't
produce it for long and was much too bright for practical use.
Over the next seven decades, other inventors also created "light
bulbs" but no designs emerged for commercial application.
More notably, in 1840, British scientist Warren de la Rue en-
closed a coiled platinum filament in a vacuum tube and passed
an electric current through it. The design was based on the con-
cept that the high melting point of platinum would allow it to
operate at high temperatures and that the evacuated chamber
would contain fewer gas molecules to react with the platinum,
improving its longevity. Although an efficient design, the cost
of the platinum made it impractical for commercial production.
In 1850 an English physicist named Joseph Wilson Swan cre-
ated a "light bulb" by enclosing carbonized paper filaments in
an evacuated glass bulb. And by 1860 he had a working proto-
type, but the lack of a good vacuum and an adequate supply of
electricity resulted in a bulb whose lifetime was much too short
to be considered an effective producer of light. However, in the
1870's better vacuum pumps became available and Swan con-
tinued experiments on light bulbs. In 1878, Swan developed a
longer lasting light bulb using a treated cotton thread that also
removed the problem of early bulb blackening.
On July 24, 1874 a Canadian patent was filed by a Toronto med-
ical electrician named Henry Woodward and a colleague
Mathew Evans. They built their lamps with different sizes and
shapes of carbon rods held between electrodes in glass cylin-
ders filled with nitrogen. Woodward and Evans attempted to
commercialize their lamp, but were unsuccessful. They even-
tually sold their patent to Edison in 1879.
In 1878, Thomas Edison began serious research into developing
a practical incandescent lamp and on October 14, 1878, Edison
filed his first patent application for "Improvement In Electric
Lights". However, he continued to test several types of material
for metal filaments to improve upon his original design and by
Nov 4, 1879, he filed another U.S. patent for an electric lamp
using "a carbon filament or strip coiled and connected ... to
platina contact wires." Although the patent described several
ways of creating the carbon filament including using "cotton
and linen thread, wood splints, papers coiled in various ways,"
it was not until several months after the patent was granted
that Edison and his team discovered that a carbonized bamboo
filament could last over 1200 hours. This discovery marked the
beginning of commercially manufactured light bulbs and in
1880, Thomas Edison's company; Edison Electric Light Com-
pany began marketing its new product.
Other Notable Dates
• 1906 - The General Electric Company was the first to
patent a method of making tungsten filaments for use in
incandescent light bulbs. Edison himself had known tung-
sten would eventually prove to be the best choice for fila-
ments in incandescent light bulbs, but in his day, the
machinery needed to produce the wire in such a fine form
was not available.
• 1910 - William David Coolidge of General Electric im-
proved the process of manufacture to make the longest
lasting tungsten filaments.
• 1920s - The first frosted light bulb is produced and ad-
justable power beam bulbs for car headlamps, and neon
• 1930s - The thirties saw the invention of little one-time
flashbulbs for photography, and the fluorescent tanning
• 1940s - The first 'soft light' incandescent bulbs.
• 1950s - Quartz glass and halogen light bulb are produced
• 1980s -- New low wattage metal halides are created
• 1990s -- Long life bulbs and Compact Fluorescent bulbs
make their debut.
Modern incandescent bulbs are not energy efficient -- less than
10% of electrical power supplied to the bulb is converted into
visible light. The remaining energy is lost as heat. However
these inefficient light bulbs are still widely used today due to
many advantages such as:
• wide, low-cost availability
• easy incorporation into electrical systems
• adaptable for small systems
• low voltage operation, such as in battery powered de-
• wide shape and size availability
However, legislation in many countries including the US have
mandated phasing out the incandescent bulb for more energy
efficient options such as compact fluorescent lamps and LED
lamps, However, there has been much resistance to these poli-
cies owing to the low cost of incandescent bulbs, the instant
availability of light and concerns of mercury contamination with
CFLs (Source History of the Light Bulb | Lighting Basics |
Bulbs.com) (Edited) www.bulbs.com/learning/history.aspx
21. The term "incandescent" (paragraph 1 line 3) is used
A. The type of light
B. The quantity of light
C. The brand of light
D. The quality of light
22. According to the writer, the belief of some that
Thomas Alva Edison invented the electric light is
A. A fact
B. An opinion
C. A fallacy
D. A parable
23. What was Warren de la Rue's contribution to the elec-
A. He designed the incandescent bulb
B. He invented the first electric battery
C. He enclosed a coiled platinum filament, in a vacuum
tube, through which electric current could pass.
D. He developed the Electric Arc Lamp
24. Based on the claims made by historians, the number
of person credited with the invention of the incandes-
cent lamp is
A. 20 persons
B. 20 persons
C. = 20 persons
D. > 20 persons
25. Humphry Davy's is BEST recognised for his
B. Invention of the electric light
C. Design of a working prototype
D. Use of a carbon filament
26. In (paragraph 4 line 2), the writer makes reference to
"a working prototype." What do you understand by
the word prototype?
A. A sample
B. A product for sale
C. A collector's item
D. An industrial product
27. Joseph Wilson Swan was renowned for
A. Inventing a commercial lamp
B. Creating a longer lasting light bulb
C. Inventing the electric light
D. Creating a ballast
28. The writer indicated that a Canadian patent was filed
by a Toronto medical electrician named Henry Wood-
ward and his colleague Mathew Evans. The word
"patent" means the SAME as
B. Certificate of ownership
C. Limited rights
29. What is the PRIMARY concern with incandescent
A. It is not cost efficient
B. It is not readily available
C. It is not energy efficient
D. It is not easily incorporated into electrical systems
30. In your assessment, what was Thomas Edison's
A. His invention of the incandescent lamp
B. The distribution of power from a centralized
C. Discovery of a carbonized bamboo filament
D. The beginning of commercially manufactured
DIRECTIONS: Read the poem carefully before attempting
the questions. Each question has four options, select the
most appropriate answer, based on what is implied or stated
in the poem.
THE CHARGE OF THE LIGHT BRIGADE
Half a league, half a league,
Half a league onward,
All in the valley of Death
Rode the six hundred.
"Forward, the Light Brigade!
Charge for the guns!" he said:
Into the valley of Death
Rode the six hundred.
"Forward, the Light Brigade!"
Was there a man dismayed?
Not though the soldier knew
Some one had blundered:
Their's not to make reply,
Their's not to reason why,
Their's but to do and die:
Into the valley of Death
Rode the six hundred.
Continued on the next page
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