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About the Striking Back at Lightning with Lasers Reading Passage
This passage examines scientific research into using high-powered laser pulses to trigger and steer lightning strikes. It covers the physics of how lasers ionise air to create conductive channels, the work of researchers including Professor Jean-Pierre Wolf and the Teramobile project team, and how this technology could replace conventional lightning rods. The passage is from Cambridge IELTS 9, Academic Test 4, Passage 1.
You should spend about 20 minutes on Questions 1–13, which are based on the passage below.
The passage contains two question types:
- True/False/Not Given : Questions 1–7
- Summary Completion : Questions 8–13
Striking Back at Lightning with Lasers : Full Reading Passage
Paragraph A
Every year, lightning kills hundreds of people and causes billions of dollars of damage. Engineers and scientists are working to develop a new kind of lightning conductor that uses laser beams rather than the traditional metal rods first used by Benjamin Franklin in the eighteenth century. Traditional lightning rods simply attract a lightning bolt to a safe grounding point. The new laser approach aims to go much further: to trigger lightning strikes on demand and direct them harmlessly into the ground.
Paragraph B
Conventional lightning rods have a poor record. Only a small proportion of lightning strikes are actually intercepted by a rod; the vast majority strike the ground elsewhere, often causing significant damage. One of the problems is that a lightning bolt will only strike a rod if the bolt happens to form directly above it. Since the precise location and time of a strike cannot be predicted, rods can do little to protect the large areas between them.
Paragraph C
The new approach uses very short, very intense laser pulses, each lasting less than a thousandth of a millionth of a second, that ionise the air along their path, creating a channel of conducting plasma. This channel acts as a kind of virtual lightning rod, guiding a lightning bolt along a chosen path. If successful, such a system could protect a large area rather than a single point.
Paragraph D
When an ultra-short laser pulse travels through air, it can create a self-sustaining structure called a filament. The filament is a very narrow thread of ionised air, only about 0.1 millimetres across, but it can extend for hundreds of metres. Unlike a conventional laser beam, which spreads as it travels, the filament maintains its narrow width over a long distance. This is because the laser power is sufficient to overcome the natural spreading tendency of light.
Paragraph E
The heat generated along this filament creates a low-density channel in the air. Since electric charge tends to move along the path of least resistance, the filament channel could steer a lightning bolt in any chosen direction. This is the core principle behind the laser lightning rod: use a filament to create a low-resistance path from the clouds to a safe grounding point.
Paragraph F
The main challenge is to make the filament extend all the way from the laser on the ground to the clouds. This requires keeping the beam tightly focused over a distance of a kilometre or more. Researchers have shown in the laboratory that it is possible to extend such channels through rain and turbulent air, which are precisely the conditions found in storm clouds. This suggests that a workable device is within reach.
Paragraph G
The laser technique is not the only alternative to the conventional lightning rod. Scientists in Japan and New Mexico have already demonstrated that it is possible to trigger lightning strikes using rockets trailed with thin copper wire. However, laser beams have obvious practical advantages over rockets. They can be fired in any direction within fractions of a second, whereas a rocket takes time to set up and can only be used once. Professor Wolf's team at the University of Geneva is currently developing a working prototype of the laser lightning rod and hopes to demonstrate it in a real thunderstorm within the next few years.
Striking Back at Lightning with Lasers Reading Questions and Answers
True/False/Not Given — Questions 1–7
Do the following statements agree with the information given in the reading passage? Write:
- TRUE — if the statement agrees with the information
- FALSE — if the statement contradicts the information
- NOT GIVEN — if there is no information on this
1.Lightning causes more financial damage globally than it does casualties.
2. Conventional lightning rods successfully intercept the majority of lightning strikes.
3. The laser system described in the passage has already been tested in real thunderstorms.
4. A laser filament maintains a narrow width over a long distance.
5. The filament is wider than 1 millimetre.
6. The heat along the laser filament creates a low-density channel in the air.
7. Professor Wolf's team has received more government funding than the rocket research group in Japan.
Summary Completion — Questions 8–13
Complete the summary below. Choose NO MORE THAN TWO WORDS from the passage for each answer.
Scientists are trying to develop a new kind of 8 ............. conductor using laser beams. The laser creates a conducting plasma 9 ............. in the air. This path is formed by a self-sustaining structure called a 10 ............. . Along this structure, the 11 ............. generated creates a low-density air channel. The challenge is extending this channel all the way to the 12 ............. . One competing method involves triggering lightning with a 13 ............. trailed with copper wire.
