Below are the NCERT Solutions for Class 11 Physics Chapter 1: Physical World, which are also available in PDF format for free download. These solutions have been prepared in accordance with the latest syllabus, NCERT books, and examination pattern recommended by CBSE, NCERT, and KVS for Class 11. The questions provided in the NCERT book for Class 11 Physics are crucial for exams, and answering them correctly can improve your scores. For more chapter-wise answers for NCERT Class 11 Physics and additional study material for all subjects, please refer to the answers provided below. Chapter 1: Physical World is a significant topic in Class 11, so make sure to utilize the answers to enhance your exam performance.
NCERT Solutions Class 11 Physics Chapter 1 Physical World
Question 1.1:
Some of the most profound statements on the nature of science have come from Albert Einstein, one of the greatest scientists 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 world around us is filled with various complex natural phenomena, making it seem incomprehensible at first glance. However, through study and observation, it has been discovered that all these phenomena are governed by fundamental physical laws. As a result, despite their complexity, the workings of the physical world are comprehensible.
Question 1.2:
“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:
The quote “Every great physical theory starts as a heresy and ends as a dogma” suggests that revolutionary ideas in science often face resistance before becoming widely accepted. Here are some examples from the history of science that validate this statement:
Heliocentrism: Back in the 16th century, everyone believed that the Earth was at the center of the universe. However, Copernicus proposed that the Sun was at the center and the planets, including Earth, revolved around it. People initially thought this idea was crazy, but eventually, after observing the movements of celestial bodies, scientists accepted heliocentrism as true.
Similarly,
The equation (E = mc2), proposed by Albert Einstein as part of his theory of special relativity, is another excellent example that fits the quote “Every great physical theory starts as a heresy and ends as a dogma.”
When Einstein first introduced this equation in 1905, it was met with skepticism and disbelief by many in the scientific community. The idea that mass could be converted into energy and vice versa seemed counterintuitive and contradicted established Newtonian physics.
However, over time, experimental evidence supporting Einstein’s theory began to accumulate, particularly with advancements in nuclear physics and the development of nuclear energy. One of the most notable confirmations came with the discovery of nuclear fission, where small amounts of mass were converted into large amounts of energy, as described by Einstein’s equation.
Today, (E = mc2) is one of the most famous equations in physics and forms the basis for understanding nuclear reactions, including those that power the sun and nuclear reactors. It serves as a cornerstone of modern physics, demonstrating how a seemingly radical idea can evolve into an accepted scientific principle through empirical evidence and theoretical understanding.
Question 1.3:
“Politics is the art of the possible”. Similarly, “Science is the art of the soluble”. Explain this beautiful aphorism on the nature and practice of science.
Answer:
The phrases “Politics is the art of the possible” and “Science is the art of the soluble” both highlight the pragmatic nature of their respective fields. While politics focuses on achieving attainable goals amidst diverse interests, science deals with problems that can be solved through systematic investigation and experimentation. It emphasizes the practical and empirical nature of scientific inquiry, where researchers aim to find solutions to tangible problems using evidence-based methods.
In other words,
the phrase “Politics is the art of the possible” implies that in politics, decisions are made based on what is achievable. Similarly, “Science is the art of the soluble” suggests that in science, problems are approached by seeking solutions that are feasible and can be solved through experimentation and observation.
Question 1.4:
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 to become a world leader in science. Name some important factors which in your view have hindered the advancement of science in India.
Answer:
Several factors have hindered India’s advancement in science despite its growing base in science and technology. These include insufficient investment in research and development, inadequate infrastructure, brain drain due to limited opportunities, bureaucratic hurdles, and a lack of effective collaboration between academia, industry, and government.
Question 1.5:
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 belief in electrons is grounded in extensive empirical evidence and rigorous scientific experimentation, whereas the existence of ghosts lacks such empirical support. Physicists infer the existence of electrons based on their observed effects and interactions, whereas claims about ghosts typically lack empirical evidence and rely on anecdotal accounts or superstition.
Question 1.6:
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 the crab shells in that area.
(b)After the sea tragedy, fishermen in that area, in a gesture of honor 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 the course of time the shape was genetically propagated. This is an example of evolution by artificial selection.
[Note: This interesting illustration taken from Carl Sagan’s ‘The Cosmos’ highlights the fact that often strange and inexplicable facts which at first sight appear supernatural actually turn out to have simple scientific explanations. Try to think of other examples of this kind].
Answer:
The scientific explanation is option (b). It suggests that the observed resemblance of crab shells to the face of a Samurai is the result of artificial selection by fishermen. By releasing crabs with such shell shapes as a gesture of honor, they unintentionally influenced the genetic makeup of the crab population over time, leading to the propagation of this particular shape. This explanation aligns with the principles of evolution and natural selection.
Question 1.7:
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:
The Industrial Revolution in England and Western Europe was propelled by several key scientific and technological advancements. These included the development of the steam engine by James Watt, improvements in iron production techniques such as the puddling process and the use of coke instead of charcoal, innovations in textile machinery like the spinning jenny and power loom, advancements in transportation with the introduction of canals and railways, and improvements in agricultural practices with the adoption of new farming technologies. These innovations transformed production processes, transportation networks, and agricultural productivity, laying the foundation for the industrialization of society.
Question 1.8:
It is often said that the world is witnessing now a second industrial revolution, which will transform society as radically as the first. List some key contemporary areas of science and technology, which are responsible for this revolution.
Answer:
Here are some of the crucial contemporary domains in science and technology poised to radically transform society:
- Advancements in high-speed computing
- Internet and remarkable progress in information technology
- Innovations in biotechnology
- Discovery of superconducting materials functioning at room temperature
- Advancements in robotics
Question 1.9:
Write in about 1000 words a fiction piece based on your speculation on the science
and technology of the twenty-second century.
Answer:
The Quantum World
Once upon a time, in the not-so-distant future of the twenty-second century, humanity embarked on a thrilling adventure into the realm of science and technology. Imagine a world where the possibilities seemed endless, where the boundaries of imagination blurred with reality, and where the future was shaped by the wonders of quantum mechanics.
In this futuristic world, quantum technology was the driving force behind humanity’s progress. Quantum computers, unlike anything seen before, were capable of processing information at speeds that were mind-bogglingly fast. These computers, powered by tiny particles called qubits, could perform calculations that would take traditional computers millennia to complete. From solving complex mathematical equations to simulating the behavior of molecules, quantum computers became the cornerstone of scientific research and innovation.
But it wasn’t just quantum computing that captured the imagination of the people. Quantum communication revolutionized the way we connected with one another. Imagine being able to send messages instantaneously across the globe, with no delays or signal interference. Quantum encryption ensured that our communications remained secure and private, protected from prying eyes and cyber threats.
In the field of medicine, quantum biology opened new frontiers in healthcare. Scientists discovered how to harness the power of quantum mechanics to manipulate and control biological systems at the molecular level. Diseases that were once considered incurable became treatable, and human lifespan extended beyond what was previously thought possible. Nanobots, tiny machines guided by quantum principles, patrolled our bodies, detecting and repairing damage at the cellular level.
Space exploration entered a golden age as humanity set its sights on the stars. Quantum propulsion systems propelled spacecraft at speeds that defied imagination, shrinking the vast distances of space and opening up the possibility of interstellar travel. Colonies flourished on distant planets and moons, as humanity ventured further into the cosmos than ever before.
But amidst the wonders of quantum technology, there were also ethical dilemmas and existential questions to consider. As humanity delved deeper into the quantum realm, we grappled with the nature of reality itself. The line between the physical and the digital blurred as virtual reality environments, powered by quantum computing, offered immersive experiences that challenged our perceptions of the world around us.
Yet, for all the challenges and uncertainties, the twenty-second century was a time of boundless optimism and exploration. Humanity stood on the brink of a new era, where the only limits were those of our imagination. As we looked towards the future, we marveled at the incredible journey that lay ahead, filled with endless possibilities and discoveries waiting to be made.
And so, dear students, as you ponder the wonders of the twenty-second century, remember that the future is yours to shape. With curiosity as your guide and imagination as your compass, there is no limit to what you can achieve. The quantum odyssey awaits, and the adventure of a lifetime is just beginning.
Question 1.10:
Attempt to formulate your ‘moral’ views on the practice of science. Imagine yourself stumbling upon a discovery, which has 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:
As per ethical standards, I believe in prioritizing the well-being of society over individual interests. If faced with a discovery posing significant harm, I would engage with experts and ethical committees to assess potential consequences. Ultimately, I would refrain from pursuing or publicizing the discovery to prevent harm to society because Science is for society, society is not for science.
Question 1.11:
Science, like any knowledge, can be put to good or bad use, depending on the user. Given below are some of the applications of science. Formulate your views on whether the particular application is good, bad or something that cannot be so clearly categorised:
(a) Mass vaccination against small pox to curb and finally eradicate this disease from the population. (This has already been successfully done in India.)
(b) Television for eradication of illiteracy and for mass communication of news and ideas.
(c) Prenatal sex determination.
(d) Computers for increase in work efficiency.
(e) Putting artificial satellites into orbits around the Earth.
(f) Development of nuclear weapons.
(g) Development of new and powerful techniques of chemical and biological warfare.
(h) Purification of water for drinking.
(i) Plastic surgery.
(j) Cloning.
Answer:
(a) Mass vaccination against smallpox: Good – It prevents disease and promotes public health.
(b) Television for eradication of illiteracy and mass communication: Good – It spreads knowledge and facilitates communication.
(c) Prenatal sex determination: Ambiguous – It can be misused for gender discrimination.
(d) Computers for increasing work efficiency: Good – It enhances productivity and facilitates tasks.
(e) Putting artificial satellites into orbits around the Earth: Good – It advances communication and scientific research.
(f) Development of nuclear weapons: Bad – It poses a threat to global security and humanity.
(g) Development of new chemical and biological warfare techniques: Bad – It endangers lives and escalates conflicts.
(h) Purification of water for drinking: Good – It promotes public health and prevents waterborne diseases.
(i) Plastic surgery: Ambiguous – It can improve quality of life but may promote unrealistic beauty standards.
(j) Cloning: Ambiguous – It has potential for medical breakthroughs but raises ethical concerns about human cloning.
Question 1.12:
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 obscurantist 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:
I’d use science to help people think more logically and clearly. By teaching about science in a simple and understandable way, we can show how things really work and why some beliefs might not make sense. We can also support scientific research to find practical solutions to problems, which can help show the value of science in our everyday lives. By working together with teachers, leaders, and everyone in the community, we can help people see the importance of thinking critically and making decisions based on evidence.
In fact, Poverty and illiteracy are the main reasons why people in India believe in superstitions. To change this, we need to address these issues first. Education is key to promoting a scientific mindset. By using scientific knowledge, we can debunk superstitions and show people the logical reasons behind events.
Question 1.13:
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:
The belief in women’s inferiority is based on unscientific notions and biases. Scientifically, there’s no basis for such claims. Many women have excelled in various fields, including science, proving their capabilities. For instance, Marie Curie won two Nobel Prizes, and Rosalind Franklin made groundbreaking contributions to DNA research. Given equal opportunities, women can excel just like men.
Question 1.14:
“It is more important to have beauty in the equations 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:
Equations that align with experimental data often possess simplicity and elegance, rendering them beautiful. In Physics, several such equations exist:
- E = mc2 (relating energy and mass)
- E=hv (relating energy and frequency of a photon)
- KE = (1/2)mv2(describing kinetic energy)
- PE=mgh (depicting potential energy)
- W=F⋅d (expressing work done)
All these equations share identical dimensions. One experiment demonstrates the energy’s reliance on speed, while another illustrates its dependency on frequency and displacement. This highlights the elegance of physics equations derived from diverse experimental setups.
Question 1.15:
Though the statement quoted above may 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:
While many physicists appreciate the elegance of simple equations, prioritizing beauty over experimental agreement undermines the essence of scientific inquiry. Physics aims to explain the natural world through empirical evidence, not just aesthetic appeal. Equations like Maxwell’s or Einstein’s may be elegant, but their true beauty lies in accurately describing physical phenomena. Prominent physicists like Einstein and Feynman emphasized the harmony between simplicity and empirical validity, urging a deeper understanding of nature’s laws.