GSEB Class 11 Physics Solutions Chapter 1 Physical World

Question 1. Some of the most profound statements on the nature of science have come from Albert Einstein, one of the greatest scientist of all time. What do you think did Einstein mean when he said “The most incomprehensible thing about the world is that it is comprehensible."
Answer: The whole of the physical world around us is very intricate due to millions of events happening. The biological world has its own intricate aspects. So the world appears hard to grasp, meaning it seems impossible to understand. Additionally, we encounter vast differences in mass, length, and time, which can amazingly be explained and shown using a few fundamental rules. Simply put, the intricate makeup of the physical world, from tiny atoms to huge cosmic scales, can be grasped using a small number of core ideas, making the physical world understandable. From this perspective, Einstein's wonder is clear. For instance, the movement of planets and satellites is explainable using Newton's laws of gravity, and these rules work everywhere in the universe.
In simple words: Einstein meant that even though the world seems very complex, it can be understood through simple scientific laws. Things like planet motion can be explained by basic rules, showing that the universe is understandable despite its apparent difficulty.

Question 2. "Every great physical theory starts as a heresy and ends as a dogma”. Give some examples from the history of science of the validity of this incisive remark?
Answer: A dogma is a widely accepted idea that only a few people doubt. It represents an official belief. However, heresy is any idea that goes against accepted beliefs and theories, creating some stir among smart people; it is a view that opposes traditional thought. It is correct that every significant physical theory begins as a heresy and concludes as a dogma. For example:
1. Thomas Young's wave theory of light began as a challenge to existing ideas and eventually became an accepted principle, before Einstein and others later swapped it with quantum theory of light.
2. In ancient times, Ptolemy suggested that the Earth stayed still, and all celestial bodies like the sun, stars, and planets moved around it. Later, an Italian scientist, Galileo, proposed that the sun was still and the Earth, with other planets, orbited it. Galileo faced consequences from the authorities of that time for sharing ideas they considered incorrect. However, Isaac Newton and Johannes Kepler later backed Galileo's idea, and it is now an accepted truth.
3. There was a concept that a body's inertia relies on its energy. Einstein presented a single formula connecting mass and energy, known as the mass-energy equivalence relation \( (E = mc^{2}) \), which is now a core principle in Physics.
In simple words: Great science ideas start as new, controversial thoughts (heresy) but end up as accepted facts (dogma) over time. For example, Galileo's idea that Earth moves around the Sun was once seen as wrong, but now it's a basic scientific truth.

Question 3. "Politics is the art of possible”. Similarly, “Science is the art of soluble." Explain this beautiful aphorism on the nature and practice of science?
Answer: In politics, anything seems achievable, as it is the craft of what can be done. It's commonly understood that politicians will make many promises and try to achieve anything to gain votes, even if they are unsure of success. While government departments might shift rapidly in politics, the fundamental laws of science do not alter quickly. Science involves an organized examination of observed facts. A scientist carefully examines these observations and then develops specific rules. For instance, Tycho Brahe spent two decades making careful observations of how planets move. Johannes Kepler then created his three well-known laws of planetary movement from this vast collection of observed data. So, the idea that science is the art of the solvable implies that many different physical processes are explainable using just a few core ideas. This suggests a pattern of unity in variety, where various occurrences can be understood and shown through a small set of basic principles. Newton's rules of gravity apply everywhere in the cosmos. These rules work for both tiny objects and for the entire solar system. The entire universe can be understood through specific principles, meaning we can explore it using a small number of rules.
In simple words: Politics is about making things happen, even if they seem hard. Science is about finding answers to problems. Scientists patiently observe things and create rules. Like Kepler found planet laws from many observations, science finds simple laws that explain many different things in the world.

Question 4. Though India now has a large base in science and technology which is fast expanding, it is still a long way from realizing its potential for becoming a world leader in science. Name some important factors, which in your view have hindered the advancement of science in India?
Answer: Here are some significant factors that have slowed India's progress toward becoming a global leader in science and technology:
1. A primary reason is that young scientists and technologists do not get the academic liberty essential for making breakthroughs in science and technology.
2. Science education in our country is managed bureaucratically. There is too much administrative and political meddling in research and technology fields.
3. There is almost no collaboration between researchers and the industrial sector, who are the primary users of new research and technology. Indian business owners have low trust in the capabilities of local scientists and choose to bring in technology from developed nations (such as the U.S.A., Japan, etc.).
4. The facilities for teaching science in Indian schools and colleges are in a very bad condition.
5. Science education is not correctly focused or guided. It requires clear guidance based on our nation's needs.
6. Enough money is not provided for scientific and technological development.
7. Our country has few job chances for students with science degrees, which leads them away from science and technology careers.
8. 'Brain drain' is another major factor that has slowed India's advancement in science and technology, causing a mass movement of scientists, doctors, and technologists to other countries.
In simple words: India has many smart people in science, but it's not yet a world leader. This is because young scientists don't have enough freedom, there's too much bureaucracy in education, not enough cooperation between researchers and industries, poor facilities, and a lack of proper direction in science education. Also, not enough money is available, there are few jobs for science students, and many skilled people leave the country.

Question 5. No physicist has ever 'seen' an 'electron'. Yet all physicists believe in the existence of electrons. An intelligent but superstitious man advances this analogy to argue that 'ghosts' exist even though no one has seen one. How will you refute his argument?
Answer: The presence of an electron is a proven truth, even though no one has physically seen one, because many events observed in our everyday lives rely on the electron's existence. Conversely, while ghosts are also not visible, there isn't any observable event that can account for their presence, nor can any occurrence be clarified by assuming ghosts exist. Therefore, it is evident that comparing these two situations is not valid.
In simple words: We know electrons are real because we see their effects in many experiments, even if we can't see them directly. But there are no real-world effects or experiments that prove ghosts exist, even though people say they see them. So, the comparison between electrons and ghosts is wrong.

Question 6. The shells of crabs found around a particular coastal location in Japan seem mostly to resemble the legendary face of a Samurai. Given below are two explanations of this observed fact. Which of these strikes you as a scientific explanation?
(a) A tragic sea accident several centuries ago drowned a young Samurai. As a tribute to his bravery, nature through its inscrutable ways immortalized his face by imprinting it on to the crab shells in ...
(b) After the sea tragedy, fisherman in that area in a gesture of honour to their dead hero, let free any crab shell caught by them which accidentally had a shape resembling the face of a Samurai. Consequently, the particular shape of the crab shell survived longer and therefore, in course of time the shape was genetically propagated. This is an example of evolution by artificial selection. fact that often strange and inexplicable facts which on the first sight appear 'supernatural' actually turn out to have simple scientific explanations. Try to think out other examples of this kind.)
Answer: (b) Following the maritime disaster, local fishermen, as a mark of respect for their fallen hero, released any crab shells they caught that happened to look like a Samurai's face. As a result, crab shells with that specific appearance lived longer, and over time, this shape was passed down through generations. This illustrates evolution guided by human intervention.
In simple words: The scientific explanation is that fishermen kept throwing back crabs that looked like Samurai faces. This meant those crabs lived longer and passed on their genes, slowly making more crabs with Samurai faces over time. This is a type of evolution where humans unintentionally pick which crabs survive.

Question 7. The Industrial Revolution in England and Western Europe more than two centuries ago was triggered by some key scientific and technological advances. What were these advances?
Answer: Here are the main scientific and technological breakthroughs that started the Industrial Revolution in England and Western Europe between 1750 A.D. and 1870 A.D.:
• The steam engine was developed using principles of heat and thermodynamics. British inventor James Watt created it in 1769 A.D., allowing industries to be built inland, far from rivers. Machines subsequently ran on steam power.
• The blast furnace, which changes poor quality iron into inexpensive steel.
• The cotton gin or spinning jenny, which removes seeds from cotton three hundred times quicker than by hand.
• Finding electricity aided in creating dynamos and motors.
• The invention of explosives assisted not only the military but also in finding minerals.
• The examination of movement and the creation of guns/cannons was informed by the study of gravity.
• The power loom, which ran on steam, was utilized for spinning threads and weaving fabric.
• The safety lamp, which allowed for safe work in mines.
In simple words: The Industrial Revolution was sparked by big scientific and tech steps between 1750 and 1870. Key inventions included the steam engine for power, the blast furnace for cheaper steel, the cotton gin for faster cotton processing, electricity for machines, explosives for mining, and power looms for weaving.

Question 8. that the world is witnessing now a second Industrial revolution which will transform the society as radically as did the first. List some key contemporary areas of science and technology which are responsible for this revolution?
Answer: Here are the main fields that will completely change today's society:
1. Creating superconducting materials that work at room temperature, which will be used in supercomputers, to make highly strong electromagnets, and for sending electrical power without any energy waste.
2. Improving infrared detectors for use in night vision, health monitoring, long-distance observation, and earth studies.
3. Farming is a basic sector that will change rural life everywhere.
4. There's a rapid change happening in information technology, covering the internet, digital media, extremely fast computers, and satellite networks.
5. Advances in biotechnology and genetic engineering could completely alter the world in the future.
6. Using satellites for various aims, exploring the chance of life on other celestial bodies, and other breakthroughs given by space science.
7. The invention of "Laser" will cause a major shift, as laser beams can send many TV programs at the same time. Controlling rockets and satellites from the ground can also be done with laser beams.
8. Lasers can also be utilized for 3D imaging, surgery without bleeding, and treating eye tumors.
In simple words: A new industrial revolution is changing society, driven by science and technology. Key areas include creating room-temperature superconductors for powerful electronics, developing infrared detectors for various uses, transforming agriculture, rapid advancements in information technology (internet, computers), progress in biotech and genetic engineering, using satellites for multiple purposes, and the invention of lasers for communication, control, and medical uses.

Question 9. Write in about 1000 words a fiction piece based on your speculation on the science and technology of the twenty second century?
Answer: Imagine a space area with such extreme heat that it ruins the superconducting abilities of the motor's electrical wires. At this point, another spacecraft, carrying both matter and antimatter, arrives to help the initial ship, which then keeps going on its journey. To state it differently: Matter can now convert into energy, and energy can convert into matter. A person from the 22nd century stands on a special machine that powers him, causing his body to vanish as energy. A fraction of a second later, he reappears perfectly fine in a location very distant from his original spot.
In simple words: Imagine a future where spaceships use powerful electric motors, but extreme heat can break them. Another ship with matter and anti-matter comes to the rescue. Also, people can turn into energy and then reappear far away, allowing instant travel.

Question 10. Attempt to formulate your 'moral' vie' s on the practice of science. Imagine yourself stumbling upon a discovery, which has a great academic interest but is certain to have nothing but dangerous consequences for the human society. How, if at all, will you resolve your dilemma?
Answer: A scientist seeks facts. A scientific find shows a natural truth. Therefore, any finding, whether beneficial or harmful to human society, should be revealed, even if moral and ethical principles might clash with scientific work. A discovery that seems risky today could prove beneficial to people in the future. We need to create strong public awareness to stop the wrong use of scientific technology. So, scientists really should have two main responsibilities:
• To find facts and share them widely.
• To stop its wrong use. For example, if cloning animals like sheep 'Dolly' were applied to humans, it would go against ethical values as it would remove the need for human reproduction. However, as a scientific fact, it must be shared openly. If, as a scientist, I discover something like this, I would prioritize the truth and make it public, regardless of moral concerns.
In simple words: Scientists aim to find the truth, and any discovery should be shared. Even if a discovery seems dangerous now, it might be useful later. Scientists should both reveal new facts and work to prevent their misuse. If I, as a scientist, found a dangerous truth, I would still make it public to keep science honest, while also trying to make sure it's not used for harm.

Question 11. Science, like any knowledge, can be put to good or bad use, depending on the user. Formulate your views on whether the particular application is good, bad or something that cannot be so clearly categorized?
1. Mass vaccination against small pox to curb and finally eradicate this disease from the population. (This has already been successfully done in India)
2. Television for eradication of illiteracy and for mass communication for news and ideas.
3. Prenatal sex determination.
4. Computers for increase in work efficiency.
5. Putting artificial satellites around the earth.
6. Development of nuclear weapons.
7. Development of new and powerful techniques of chemical and biological warfare.
8. Purification of water for drinking.
9. Plastic surgery.
10. Cloning.
Answer:
1. Positive
2. Positive
3. Negative
4. Positive
5. Positive
6. Negative
7. Negative
8. Positive
9. Positive
10. An application that cannot be easily classified as good or bad.
In simple words: Science can be used for good or bad. Mass vaccination, TV for education, computers for efficiency, satellites, water purification, and plastic surgery are generally positive uses. Prenatal sex determination, nuclear weapons, and chemical/biological warfare are negative. Cloning is something that is hard to categorize simply as good or bad, as it has complex implications.

Question 12. India has had a long and unbroken tradition of great scholarship-in mathematics, astronomy, linguistics, logic and ethics. Yet, in parallel with this, several superstitious and obscurantistic attitudes and practices flourished in our society and unfortunately continue even today-among many educated people too. How will you use your knowledge of science to develop strategies to counter these attitudes?
Answer: In India, irrational customs and superstitious beliefs have intricate and ancient roots within society, and there's no quick solution to remove them. A few reasons that lead to these practices include:
1. The caste system.
2. A desire to control others by keeping them uneducated.
3. Withholding education from bigger parts of society.
4. The personal gains of governing and landowning groups.
5. People's lack of scientific understanding.
To address these viewpoints, advancements in science and technology should be used to teach people on a large scale, which can be achieved through electronic mass media such as radio, TV, newspapers, and science displays. Parents should be urged to send their children to school for learning. This can be fostered by sparking their curiosity to learn more about their surroundings, encouraging them not to trust superstitions and incorrect beliefs. Science should prioritize finding a way to manage our country's population growth, so that people will trust scientific methods and processes.
In simple words: India has a history of learning but also has many superstitions, even among educated people. To fight this, we can use science and technology to educate everyone through media like TV and newspapers, and through science shows. Parents should send their kids to school to build curiosity and stop believing false things. Science should also help control population growth, which will make people trust scientific methods more.

Question 13. Though the law gives women equal status in India, many people hold unscientific views on a woman's innate nature, capacity and intelligence, and in practice give them a secondary status and role. Demolish this view using scientific arguments, and by quoting examples of great women in science and other spheres and persuade yourself and others that, given equal opportunity, women are on par with men?
Answer: Nature has created minor distinctions in the physical structure and emotions of men and women. Women show no difference in their ability for: 1. Making choices 2. Taking on duties 3. Performing tasks and 4. Intellectual ability. It is a biological truth that human brain development relies not on sex but on dietary intake and genetic factors. She possesses patience and the ability to handle pressure as extra traits compared to men. This makes her better suited for management and public engagement roles. Her ability to convince others makes her a superb educator. Test results from different boards, universities, and public examinations show that girls consistently outperform boys, providing clear scientific proof that women are not less capable than men in any field, such as sports, climbing mountains like the Himalayas, or practicing medicine. We can provide instances of highly accomplished women in science and other areas. Names such as Marie Curie, Sarojini Naidu, Indira Gandhi, Benazir Bhutto, Mrs. Bhandarnaik, Mother Teresa, Margaret Thatcher, Lata Mangeshkar, covering fields from science to management, and Rani Lakshmibai, the warrior queen, are globally recognized figures who demonstrated greater ability than men. Therefore, we can conclude that, from a scientific standpoint, women are equal to men. Furthermore, the dietary intake during pregnancy and after birth greatly affects how the human mind develops. If both genders are given the same chances, then the female mind will work just as effectively as the male mind.
In simple words: Women are equal to men, despite what some unscientific views suggest. Biologically, brain development depends on nutrition and genes, not gender. Women show the same capacity for decision-making, responsibility, work, and intelligence. They also have extra qualities like patience and persuasion. Exam results often show girls excelling, and many great women like Marie Curie and Indira Gandhi have proven their abilities in various fields. With equal chances, women's minds are just as capable as men's.

Question 14. "It is more important to have beauty in the equation of physics than to have them agree with experiments." The great British physicist P.A.M. Dirac held this view. Criticize this statement. Look out for some equations and results in this book which strike you as beautiful?
Answer: Dirac's perspective, stating that 'It is more crucial for a physics equation to possess elegance than to match experimental results,' is accurate. The formula needs to be straightforward and concise, yet it must capture the entire idea, making it elegant. The stated remark contains no inconsistencies. A physics equation that aligns with experimental findings will inherently be both straightforward and elegant. The formula \( E = mc^{2} \) is a prime instance of an elegant equation. Another formula, \( F = G \), is also clear and elegant because it applies universally, meaning it holds true for two small objects and for planets, and the value of G remains constant in all situations. Therefore, physics equations possess greater elegance. \( F = G \) has faced challenges at the cosmic scale, based on observations in specific scenarios.
In simple words: Dirac's idea that an equation's beauty matters more than its experimental fit is right. A good equation should be simple, short, and explain a whole concept, which makes it beautiful. Equations that match experiments are naturally both simple and elegant. Examples are \( E = mc^{2} \) and \( F = G \), which are simple, universal, and beautiful, even if \( F = G \) has some complex cases at a cosmic scale.

Question 15. Though the statement quoted above be disputed, most physicists do have a feeling that the great laws of physics are at once simple and beautiful. Some of the notable physicists, besides Dirac, who have articulated this feeling are Einstein, Bohr, Heisenberg, Chandrasekhar and Feynman. You are urged to make special efforts to get access to the general books and writings by these and other great masters of physics (See the Bibliography at the end of this book). Their writings are truly inspiring.
Answer: It is certain that the major principles of physics are both simple and elegant, and they are also straightforward to comprehend. For instance, consider a few of these:
1. \( E = mc^{2} \) is Einstein's well-known relationship for mass-energy equivalence, which significantly affects not only different physical events but also human existence.
2. Planck's quantum principle, meaning \( E = hv \), is likewise a straightforward and elegant formula, and it stands as a fundamental law of physics.
3. \( \Delta\chi \cdot \Delta\rho \ge \frac{1}{2}\cdot\frac{h}{2\pi} \) or \( \Delta E \cdot \Delta t \ge \frac{1}{2}\cdot\frac{h}{2\pi} \) represents Heisenberg's Uncertainty Principle, which is also quite simple, elegant, and engaging. It directly follows from the dual behavior of matter.
4. \( \lambda = \frac{h}{mv} \) is another well-known physics equation, called the de-Broglie equation. It is also straightforward and elegant.
In simple words: Many physicists feel that physics laws are simple and beautiful. For example, Einstein's \( E = mc^{2} \) shows how mass and energy are connected. Planck's quantum rule \( E = hv \) is also very simple. Heisenberg's Uncertainty Principle, \( \Delta\chi \cdot \Delta\rho \ge \frac{1}{2}\cdot\frac{h}{2\pi} \), shows limits to what we can know, and de-Broglie's equation \( \lambda = \frac{h}{mv} \) explains particle-wave duality simply.

Question 16. Textbooks on science may give you a wrong impression that studying science is dry and all too serious and that scientists are absent minded introverts who never laugh or grin. This image of science and scientists is patently false. Scientists like any other group of humans have their share of humorists, and many have led their lives with a great sense of fun and adventure even as they seriously pursued their scientific work. Two great physicists of this genre are Gamow and Feynman. You will enjoy reading their books listed in the Bibliography?
Answer: This is not really a task, but rather a statement of truth. We can also mention other physicists who were known for their humor. These include C. V. Raman, Homi Jahangir Bhabha, Einstein, and Bohr. India has many politicians, such as M.M. Joshi and V.P. Singh, who are also physicists. President A.P.J. Abdul Kalam was also a distinguished nuclear scientist.
In simple words: Textbooks might make science seem boring, but that's wrong. Scientists are often fun and adventurous people. Famous physicists like Gamow and Feynman were known for their humor. Other well-known physicists like C. V. Raman, Homi Jahangir Bhabha, Einstein, and Bohr also had a lighter side. Even in India, some politicians, like M.M. Joshi and V.P. Singh, are physicists, and President A.P.J. Abdul Kalam was a great nuclear scientist.