Twisted Light – IELTS Reading Answers

With diligent practice, the IELTS Reading Module can be your highest-scoring section. To achieve the best results, you need to understand how to approach and answer the different question types in the Reading Module. By solving and reviewing sample reading questions from past IELTS papers, you can ensure that your reading skills are up to par.

The Academic passage, ‘Twisted Light’, is a reading passage that appeared in an IELTS Test. Ideally, you should not spend more than 20 minutes on a passage. Let’s see how easy this passage is for you and if you’re able to make it in 20 minutes. If not, try more IELTS reading practice tests from IELTSMaterial.com.

‘Twisted Light’ is a part of an IELTS Academic reading test. The question types found in this passage are as follows:

• Matching Information (Q. 1-6)
• Summary Completion (Q. 7-11)

Reading Passage 

Twisted Light 

A Why is your mobile phone or wireless signal so slow? If you ask your service provider, they’ll tell you that it’s the bandwidth. We’re running out of signal space on the wireless spectrum. All wireless communications travel through radio or optical frequencies: your TV or radio programmes, your GPS device that helps you find your way, your mobile and smartphone, laptop and wirelessly connected PC. The demands from users and industry on a limited resource, the wireless spectrum, are growing daily and are closely regulated. The reason is that two users cannot use the same signal: think about radio stations, which have to operate on different frequencies otherwise they cause interference with each other. Likewise mobile phone operators cannot transit over the same frequency in the same market at the same time. Government-controlled agencies grant licences to use the wireless spectrum but if a wireless company wants to add more spectrum to its service to boost its capacity, it’s likely to be disappointed as there isn’t much more available. What is needed is a way of pushing more data through the same amount of bandwidth.

B Now scientists may have found a way of manipulating light waves to carry more information: potentially enough for users to be able to download a film onto a smartphone in a single second. By twisting light waves, scientists could possibly transmit data at speeds of 2.56 terrabits per second: that’s 85,000 times faster than the 30 megabits per second currently possible. To put it another way, this is the same as transmitting 70 DVDs through the air in about a second. Researchers based in America, China, Israel and Pakistan have built on previous research from Sweden, which negates the need for more bandwidth by making better use of the spectrum. The basis of the research is to manipulate the properties of light.

C One property of light is wavelength: lasers, radio waves, microwaves are simply different wavelengths of light. Light is made up of photons and photons have two other properties that define a beam of light: spin angular momentum and orbital angular momentum. A good way of thinking about how photons travel is to think of the orbit of a planet: it spins around on its axis (spin angular momentum), and at the same time the planet is also revolving around the sun (orbital angular momentum). The latter force means that light can be twisted around its axis of travel to take the shape of a spiral or a corkscrew. At the centre of the spiral the light waves cancel each other out, leaving darkness in the middle, called an optical vortex. When light travels, it is formed into a spiral shape and it can be manipulated. There are infinite possibilities for ways in which the photon can be made to spiral: clockwise, counterclockwise, tight spirals or loose ones. Each of these spiral states can be uniquely identified but, more importantly for wireless communication, the spirals can be wrapped up within each other — or multiplexed — into a single beam. The beam can be transmitted and unwound at the receiving end to get the data streams back out again, essentially doubling or trebling or even quadrupling the bandwidth.

D  Scientists have been twisting light since the 1970s, and the spin angular momentum of waves is already manipulated in standard wireless communication. For years, Bo Thide of the Swedish Institute of Space Physics theorised that the orbital angular momentum could be used to create the spiral signal or as Thiele calls it a ‘radio vortex’. Then in an experiment in Venice, his team transmitted two signals simultaneously on the same frequency over a distance of 442 metres. Following on from this, researchers in America, China, Israel and Pakistan, led by Alan Wilner, twisted together eight light data streams, each stream with its own level of orbital angular momentum twist. One of the streams was transmitted as a thin stream while the others were transmitted around the outside. The data beam was then sent to a receiver and untwisted to recover the data.

E The achievement is very exciting for developers of wireless network technology as the useful spectrum of frequencies is largely used up. The orbital angular momentum model would allow for an infinite number of data transmissions without taking up any more of the spectrum. There is a problem, however: researchers can only transmit the data stream one metre, which is an insignificant distance for communication purposes. The short transmission range is due to turbulence in the atmosphere, which disrupts the signal as the light hits air molecules. But the scientists are planning to be able to send the beam considerably further. One idea is to create links every kilometre to extend the network. Another is to build high-speed satellite communication links where the atmospheric problems would not affect the signal. Another possibility is to adapt the technology for fibre-optic use, the way data is currently transmitted over the Internet. Unfortunately, at this point standard fibre-optic cables are not capable of carrying multichannel signals and fibre-optic cables that can carry the signal experience problems of interference between channels as they carry data with high bit-rates.

F Nevertheless, exploiting the orbital angular momentum gives scientists options that could lead to significant increases in data transfer; even a modest increase in the existing data transfer rate is worthwhile. Furthermore, very often technology is pulled along by innovative research so a novel solution to carrying the data-rich signal may not be far behind.

Questions 1- 6

1 changing light waves to increase capacity

2 a practical demonstration of the new technology

3 use of the wireless spectrum needing to be monitored closely

4 overcoming the problem of the short range of the new signal

5 improvements in data transmission, possibly leading to technological breakthroughs

6 the prospect of saving people a lot of time

Questions 7-11

Researchers are looking for a way of using the 7……………… more efficiently. One option is to transmit signals that are twisted into 8……………… and wrapping them together, or 9……………… them. This is still problematic on earth due to 10……………… but scientists hope that 11………………cable technology will catch up with the research breakthrough.

Answers of Twisted Light Reading Answer with Location and Explanation 

1 Answer: C

Question type: Matching Information

Answer location: Paragraph C, line 9

Answer explanation: In the third paragraph, it is given that “The beam can be transmitted and unwound at the receiving end to get the data streams back out again, essentially doubling or trebling or even quadrupling the bandwidth.”. This section points out that changes (unwound at the receiving end) can be made to the light waves (beam) to increase its capacity (doubling, trebling or even quadrupling the bandwidth). Hence, the answer is C.

2 Answer: D

Question type: Matching Information

Answer location: Paragraph D, line 3

Answer explanation: In the specified paragraph, it is given that “Then in an experiment in Venice, his team transmitted two signals simultaneously on the same frequency over a distance of 442 metres.”. It can be noted that in the fourth paragraph, there is a mention of a practical experiment based on the theory of Bo Thide of the Swedish Institute of Space Physics that showcased the new technology, which is called the spiral signal or as Thiele calls it a ‘radio vortex’. Hence, the answer is D

3 Answer: A

Question type: Matching Information

Answer location: Paragraph A, line 5

Answer explanation: In the first paragraph, it is specified that “The demands from users and industry on a limited resource, the wireless spectrum, are growing daily and are closely regulated.”. From this reference, it can be concluded that due to the increasing demand of bandwidth, the use of wireless spectrum needs to be monitored (closely regulated). Hence, the answer is A.

4 Answer: E

Question type: Matching Information

Answer location: Paragraph E, line 6-line 8

Answer explanation: In the cited lines, it is stated that “One idea is to create links every kilometre to extend the network. Another is to build high-speed satellite communication links where the atmospheric problems would not affect the signal. Another possibility is to adapt the technology for fibre-optic use, the way data is currently transmitted over the Internet.”. Though there is a problem with the short range of the new signal, researchers have come up with three alternative ways to solve it as mentioned in the quoted lines. Hence, the answer is E.

5 Answer: F

Question type: Matching Information

Answer location: Paragraph F

Answer explanation: In the last paragraph, it is given that “Nevertheless, exploiting the orbital angular momentum gives scientists options that could lead to significant increases in data transfer; even a modest increase in the existing data transfer rate is worthwhile…so a novel solution to carrying the data-rich signal may not be far behind.”. It can be concluded that the concluding paragraph provides information on the improvements in data transmission (significant increase in data transfer) which could lead to technological breakthroughs (data-rich signal). Hence, the answer is F.

Tips for Answering the Question Types in the Twisted Light Reading Passage 

Let us check out some quick tips to answer the types of questions in the Twisted Light IELTS Reading Answers passage.

Matching Information:

IELTS Reading Matching Information questions are a type of question that tests your ability to identify and match information in a passage. You will be given a list of statements or questions, and a list of paragraphs from the passage. Your task is to match each statement or question to the paragraph in the passage that provides the most relevant information. To answer Matching Information questions, you should:

• Read the questions carefully and try to understand what the key information is.
• Think of ways to express the key information in different words.
• Scan the paragraphs to find the key information or its paraphrases.
• The answers are not in the same order as the questions, so you need to use your judgement to match the correct answer to each question.
• Your answer should be a letter, not words.
• Start with the easiest questions first to build your confidence.

Summary Completion:

Summary Completion IELTS Reading questions test your ability to skim, scan, and deeply read a passage to identify key information and fill in blanks in a summary, using words and phrases from the text. Here’s a step-by-step guide to answering these questions:

• Read the instructions carefully to make sure you understand what you’re being asked to do.
• Skim the summary to get a general idea of what it’s about.
• Read the summary more closely and try to predict the type of word or phrase needed to fill in each blank.
• If you’re given a list of words or phrases to choose from, eliminate any that you know are not correct.
• Scan the text for the information you need to fill in the blanks.
• Pay attention to the context of the surrounding words and phrases to make sure your answer makes sense.

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