IELTS Academic Reading Practice Test 73

In the autumn of 1895, Wilhelm Conrad Röntgen, professor of physics at the University of Würzburg, was experimenting with a cathode-ray tube in a darkened laboratory. The tube was covered with black cardboard, yet he noticed that a screen coated with a fluorescent substance began to glow on a nearby bench. Something was passing through materials that blocked ordinary light. Röntgen repeated the observation several times, convinced that he had found a new kind of radiation. Because its nature was unknown, he called it X-radiation, or X-rays.

Over the following weeks, Röntgen explored the properties of the new rays. He found that they travelled in straight lines and passed through materials such as paper, wood and human flesh, while denser substances such as bone and metal absorbed them more strongly. In one famous experiment he placed his wife's hand between the tube and a photographic plate. After a lengthy exposure, the resulting image showed the bones of her hand clearly, along with the dark shadow of her wedding ring. The picture was quickly reproduced and helped convince scientists and the public that X-rays were real.

Röntgen presented his findings in a paper submitted in the final week of 1895. Newspapers across Europe and North America reported the discovery, and within months doctors were using X-ray equipment to locate bullets, broken bones and swallowed objects. The apparatus was relatively simple: it required a high-voltage supply, a vacuum tube and a fluorescent screen or photographic plate, so laboratories and hospitals could build or buy their own machines. This rapid spread made X-rays one of the most quickly adopted medical innovations in history.

The early enthusiasm was accompanied by serious harm. Because X-rays are a form of ionizing radiation, they carry enough energy to damage living tissue and alter DNA. Operators who repeatedly held their hands in the beam suffered burns, hair loss and ulcers; some later developed cancer, and a number of early experimenters lost fingers. At first, no one understood the cause. By the 1920s and 1930s, standard protective measures such as lead aprons, shielding and limits on exposure time began to be introduced.

The physical nature of X-rays was clarified gradually. They are electromagnetic waves, similar to visible light and radio waves, but with much shorter wavelengths and therefore much higher energy. They are produced when electrons accelerated to high speeds strike a metal target, usually tungsten, and are suddenly slowed down. In a modern X-ray tube, a heated cathode releases electrons, a high voltage accelerates them, and their rapid deceleration at the anode generates X-rays.

Medical diagnosis was transformed. Chest radiographs became a routine way to detect tuberculosis, pneumonia and heart enlargement. Dentists used X-rays to reveal decay hidden between teeth, and orthopaedic surgeons relied on them to assess fractures and joint disorders. During the First World War, mobile X-ray units were taken close to the front lines to find bullets and shrapnel. In the 1970s, the development of computed tomography, or CT, used X-rays taken from many angles and computer processing to create cross-sectional images of the body, greatly expanding diagnostic possibilities.

The penetrating power of X-rays also proved valuable beyond medicine. Airport security scanners use them to inspect luggage; industrial radiographers examine welds, pipes and aircraft components for hidden cracks; and in research laboratories, X-ray diffraction reveals the atomic structure of materials such as crystals and complex biological molecules. The technique played an important part in working out the structure of DNA in the early 1950s, linking physics, chemistry and biology.

Modern radiology has greatly reduced the risks. Digital detectors require far less radiation than photographic film, and the beam is tightly limited to the area being examined. Workers wear monitors that record cumulative exposure, and patients are exposed only when the expected benefit outweighs the risk. Complete safety is impossible, because no dose of ionizing radiation is entirely without effect, but carefully controlled use has made X-rays far safer than in the early years.

Röntgen refused to patent his discovery, believing that it should be freely available for the benefit of humanity. In 1901 he received the first Nobel Prize in Physics. More than a century later, X-rays remain one of the most widely used tools in medicine, industry and science. His accidental observation in a darkened laboratory did more than reveal the bones of a hand; it made the invisible interior of matter open to inspection.

The V-shaped flocks of geese, ibises and pelicans are among the most familiar sights of the migration season, yet the precise function of the formation has been debated for decades. Early observers proposed that the shape allowed birds to keep one another in view, that it reduced the risk of collision, or that it enabled younger birds to follow experienced leaders. Each suggestion had some appeal, but none could explain why the birds chose a V rather than a simple line or cluster.

Aerodynamic theory offered a more convincing account. A flying wing generates lift, but it also creates a pair of trailing vortices that rotate in opposite directions. Between these vortices, air is pushed downward; outside them, air is pushed upward. A bird that places itself slightly behind and to one side of the bird in front can therefore ride in rising air, while avoiding the downwash directly behind. In effect, the leading bird leaves a small region of useful upwash, and a trailing bird can exploit it by placing its wing in that region.

Early support for this idea came from measurements of heart rate in birds flying in formation. Scientists reasoned that if trailing birds saved energy, their muscles would work less hard and the saving would show up in a lower heartbeat. The results suggested that birds in a V did indeed use less energy than solitary birds, though the techniques of the time made the evidence difficult to interpret. Laboratory studies of fixed-wing aircraft had long shown that aircraft could capture a similar benefit from flying in close lateral positions.

Studying wild flocks, however, was extremely difficult. It was hard to measure the exact position and wing motion of every bird at the same time, and it was impossible to know what each bird was feeling. Modern miniature instruments changed this. Accelerometers could record wingbeat timing, GPS loggers could track position, and heart-rate monitors could reveal metabolic effort. Researchers began attaching such devices to birds, sometimes using animals that had been raised in captivity and trained to follow an aircraft.

In one widely reported project, juvenile Northern bald ibises—an endangered species being reintroduced to Europe—were taught to migrate with a powered aircraft. Lightweight loggers recorded their flight. The ibises spent much of the flight in a V, and the data showed that they positioned themselves close to the place predicted to offer the strongest upwash. More remarkably, they adjusted the phase of their wingbeats so that their wingtips moved in time with the changing airflow, suggesting that they were actively tracking the beneficial region rather than simply gliding.

Researchers found that the birds did not keep a fixed position. They frequently swapped roles, with the leading bird dropping back and another taking its place. This sharing of the most demanding position may allow the flock to spread the cost of flight. It also indicates that at least some aspect of the formation is cooperative, although each bird's immediate motivation may simply be to lower its own effort. A similar pattern is seen in human cyclists, who take turns at the front to share the burden of air resistance.

Not all migrants travel in a V. Species with shorter wings, or those that fly in small, dense flocks, often use other formations. The V is most common among large, long-range birds that rely on extended powered flight, such as geese, pelicans, cranes and ibises. Gliding seabirds may arrange themselves in lines across the wind, while starlings and shorebirds form twisting flocks whose movements are thought to protect against predators. The energy-saving V is therefore only one solution among many.

The findings also matter for engineers. Airlines have long understood that aircraft flying in formation could reduce fuel consumption by taking advantage of the same aerodynamic effect. In practice, passenger aircraft do not travel close enough for such savings because of safety rules and passenger comfort. Researchers working on military aircraft and autonomous drones continue to study bird formations, hoping that the rules birds use could help design future systems that reduce emissions and energy use.

Despite decades of study, some questions remain. It is not yet clear how birds sense the exact movements of air produced by the birds around them, nor how much of the behaviour is learned from other flock members. What is certain is that the elegant V is far more than a visual habit: it is a behaviour shaped by the invisible geometry of airflow.

The research has also refined our understanding of what a formation actually is. The V is not a rigid arrangement but a flexible, shifting pattern in which each bird continually adjusts its position and wingbeat. Such dynamic coordination, made visible by modern tracking technology, helps explain how animals with small brains can solve an aerodynamic problem that engineers still find difficult to imitate.

For many adults, reading for pleasure is inseparable from childhood memories of being lost in a book. Yet in recent years, teachers, parents and policymakers have worried that this form of reading is disappearing. Surveys regularly report that children and teenagers spend more time on screens and less time reading books solely for enjoyment. The concern is understandable, but the debate has sometimes been framed too narrowly: reading for pleasure is often defended as a way of raising achievement, when its value may be far broader.

There is nevertheless substantial evidence that pleasure reading supports academic development. Longitudinal studies have found that children who read frequently and independently build larger vocabularies and show stronger reading comprehension than their peers, even after prior ability and family background are taken into account. The relationship is not difficult to explain. Written texts contain far rarer words than everyday speech or television, and the habit gives pupils repeated, spaced encounters with language, which helps across the curriculum.

The benefits are not confined to language. Research on adults has associated reading literary fiction with improved performance on tests of emotion recognition and perspective-taking. The explanation usually offered is that fiction invites readers to imagine the mental states of characters, and this imaginative exercise resembles the social thinking required in daily life. However, such effects are typically small and do not appear after every kind of story, and the evidence is largely correlational. It is therefore hard to determine whether reading causes these gains or whether socially skilled people simply choose to read more.

Reading for pleasure may also offer psychological benefits. Bibliotherapy, in which books are recommended to support mental health, has a long history, although formal evaluations are limited. A number of studies suggest that recreational reading can lower self-reported stress, and some healthcare professionals encourage patients to read before sleep as part of a relaxing routine. Screen reading may be different: notifications, hyperlinks and advertising compete for attention, and many readers report that they skim more and remember less when they read on a device.

Yet there is a risk of romanticising the printed book. Digital texts can provide access to readers who would otherwise have few books, and the quality of reading may depend more on the reader's purpose than on the medium. A person who scrolls through a poorly reasoned article is not reading deeply simply because the words appear on paper, and a teenager who becomes absorbed in an online serial is certainly reading for pleasure. The challenge is not to oppose digital reading, but to protect the conditions for sustained attention in both print and digital forms.

Those conditions are not equally distributed. International assessments have repeatedly found that children from advantaged homes report more reading for pleasure and have access to more books. Public libraries and school libraries can partly close this gap, but in many countries their budgets have been cut. When schools reduce reading to a set of comprehension exercises or reward systems, they may also discourage the very curiosity that leads pupils to choose a book for themselves. A love of reading cannot be enforced, but it can be made more likely by giving young people time, choice and books that reflect their lives.

Critics sometimes argue that the campaign for reading for pleasure is elitist, because it assumes that everyone enjoys solitary, bookish activity. There is some truth in this. Not every reader likes fiction, and not every form of valuable reading looks like a novel. Magazines, graphic novels, audiobooks and factual websites all provide routes into confident reading. Teachers who value pleasure recognise that the goal is not to produce identical readers, but to help each student find some form of reading that does not feel like a chore.

Adults influence the habit more than they realise. Children who see family members reading, and who are read to in the early years, gain background knowledge and vocabulary that make later independent reading less tiring. For older students, adults who discuss what they are reading, recommend titles and take an interest in a young person's choices do more to sustain the habit than any number of required book reports. Choice and example are more powerful than instruction alone.

In my view, reading for pleasure should not be treated as an optional extra or as a luxury that can be dropped when schedules tighten. It is one of the few activities that simultaneously builds language, exercises attention, and gives access to the inner lives of others. Schools cannot make anyone love books, but they can protect quiet periods, stock libraries generously and let students choose. If we care about long-term educational outcomes, we should measure them not only by test scores but also by whether children leave school still curious enough to pick up a book.