Class 11 Physics Ch 1-Physical World Solutions (NCERT )

Step-by-step NCERT solutions for Class 11 Physics Chapter 1: Physical World — all 16 exercise questions answered in full, plus a free self-check quiz at the end.

This page gives you the complete Class 11 Physics Ch 1-Physical World Solutions for the NCERT textbook, covering every exercise question with clear, accurate explanations. Chapter 1 introduces the scope of physics, its relationship with technology and society, and some of the philosophical questions around scientific discovery — so many of the answers focus on reasoning and explanation rather than calculation.

Class 11 Physics Ch 1-Physical World Solutions – Question 1.1: Einstein’s “Incomprehensible” Quote

What do you think did Einstein mean when he said: “The most incomprehensible thing about the world is that it is comprehensible”?

Answer:

The physical world is complex, and the biological world has its own complexities on top of that. Vastly different orders of magnitude are involved across space, time, and mass. Despite all this complexity, almost all physical phenomena can be expressed in terms of a handful of basic laws. Viewed in this light, Einstein’s statement becomes clear — it is remarkable that such an intricate universe can be understood through simple, unifying principles.

Question 1.2: “Every Great Physical Theory Starts as a Heresy”

Give some examples from the history of science of the validity of this incisive remark.

Answer:

A common everyday observation is that light travels in a straight line. When Huygens proposed his wave theory of light, it went against the accepted belief of the time. However, it eventually became widely accepted (“dogma”) once reflection, refraction, and other phenomena were successfully explained using the wave theory. Later, the discovery of the photoelectric effect showed that the wave theory alone could not explain all observations, leading to the conclusion that light has a dual nature — behaving as both a wave and a particle. Similar examples can be found throughout the history of science, such as the initial rejection and eventual acceptance of heliocentrism, continental drift, and the theory of evolution.

Question 1.3: “Science Is the Art of the Soluble”

Explain this aphorism on the nature and practice of science.

Answer:

Science is a systematic study of observations. A scientist patiently analyzes these observations and derives laws from them. As an example, Tycho Brahe spent twenty years recording detailed observations of planetary motion. It was from this vast reservoir of data that Kepler formulated his three famous laws of planetary motion. In this sense, science is the art of the soluble — it works with what can be observed, measured, and explained — just as politics is the art of what is practically achievable.

Question 1.4: Factors Hindering Science in India

Name some important factors which, in your view, have hindered the advancement of science in India.

Answer:

• Lack of infrastructure and funding for quality scientific research.
• Science education that is not properly oriented or directed toward the country’s actual needs.
• Poor reach of science education in rural areas, depriving a large section of the population of its benefits.
• Comparatively poor pay scales and facilities for scientists relative to other professions.
• A society still influenced by superstition and tradition, making it slower to adopt new scientific ideas.
• Weak coordination between researchers and industry, with industrialists often having limited confidence in domestic research and innovation.

Question 1.5: Electrons vs. Ghosts

An intelligent but superstitious man argues that ‘ghosts’ exist since no one has ‘seen’ an electron either. How will you refute his argument?

Answer:

While no one has directly seen an electron, countless phenomena that depend on the existence of electrons — such as electric current, cathode rays, and the photoelectric effect — have been precisely predicted and repeatedly verified through experiment. In contrast, there is no phenomenon that can only be explained by assuming the existence of ghosts, and no experiment reliably detects or predicts their behavior. The comparison therefore fails: belief in electrons rests on consistent, testable, reproducible evidence, whereas belief in ghosts does not.

Class 11 Physics Ch 1-Physical World Solutions – Question 1.6: The Samurai Crab

Crab shells near a Japanese coastal location resemble the legendary face of a Samurai. Two explanations are given below — which is scientific?

(a) A tragic sea accident drowned a young Samurai; nature immortalized his face on the crab shells as a tribute.
(b) Fishermen, out of superstitious reverence, avoided catching face-patterned crabs and threw them back. Over generations, this selective sparing made the face-like pattern increasingly common.

Answer:

Explanation (b) is scientific. It relies on a natural, mechanistic process — a form of unintentional selection — where a chance variation was repeatedly favored by human behavior over many generations, gradually making that pattern dominant in the population. Explanation (a) invokes a supernatural cause with no testable basis and is therefore not scientific.

Question 1.7: Science Behind the Industrial Revolution

What key scientific and technological advances triggered the industrial revolution in England and Western Europe?

Answer:

Key advances included the application of heat and thermodynamics to develop the steam engine, the discovery of electricity leading to the design of dynamos and motors, and the study of gravitation and mechanics, which advanced the design of machinery, guns, and cannons. These developments — combined with progress in chemistry, physics, and the natural sciences more broadly — gave England and Western Europe a significant technological and military advantage, contributing to their dominant global position during that era.

Question 1.8: The Second Industrial Revolution

List some key contemporary areas of science and technology responsible for a “second industrial revolution.”

Answer:

• The design of super-fast computers.
• Biotechnology.
• Developments in space science.
• The development of room-temperature superconducting materials.
• Advances in electronics, information technology, and nanotechnology.

Question 1.9: Science Fiction — The 22nd Century

Write, in about 100 words, a fiction piece based on your speculation on the science and technology of the twenty-second century.

Answer:

By the twenty-second century, genetic engineering may allow the deliberate design of organisms with specific traits, along with high-yielding crop varieties suited to a changing climate. Advances in laser and energy technologies could reshape industry and daily life. Space travel may reach speeds unimaginable today, with humanity establishing settlements on other planets and possibly encountering other forms of life. Communication technology could allow two people anywhere on the globe — or on the Moon — to speak face-to-face in real time. Medicine may partially conquer many diseases and significantly slow the ageing process.

Question 1.10: The Moral Dilemma of Dangerous Discoveries

Imagine you discover something of great academic interest but with dangerous consequences for society. How do you resolve this dilemma?

Answer:

A scientist’s fundamental aim is to seek and reveal truth. A scientific discovery uncovers a fact of nature, and in principle, such truths should not be suppressed — a discovery that appears dangerous today may prove beneficial to humanity later, and vice versa. However, to guard against misuse, the scientific community should couple discovery with responsibility: building public awareness, advocating for ethical safeguards and regulation, and engaging openly with society about risks and applications. A scientist’s role is twofold — to pursue truth, and to help ensure that truth is not misused.

Question 1.11: Smallpox Vaccination — Good or Bad Science?

Was mass vaccination against smallpox a good, bad, or uncategorizable use of science?

Answer — View: Unquestionably good.

• Eradication of suffering: Smallpox caused severe disfigurement, blindness, and death for millions. Systematic global vaccination led to its complete eradication by 1980.
• A public health triumph: It shows how medical science, applied globally and ethically, can permanently eliminate a major disease burden.
• Preventive protection: Vaccination protects proactively and builds herd immunity, indirectly protecting even those who cannot be vaccinated.

Because its sole outcome was the preservation of life and permanent disease elimination, this application is a clear, unambiguous force for good.

Question 1.12: Countering Superstition with Science

How will you use your knowledge of science to counter superstitious and obscurantist attitudes in society?

Answer:

Mass media — radio, television, newspapers, and increasingly the internet — can be used to popularize scientific explanations of everyday phenomena. Education systems should emphasize critical thinking and the scientific method from an early age. By explaining the real, verifiable causes behind events otherwise attributed to superstition, society can gradually reduce reliance on unscientific beliefs.

Question 1.13: Women in Science and Society

Demolish the view that women hold secondary intellectual status, using scientific arguments and examples of great women achievers.

Answer:

There is no scientific basis for a difference in the intellectual capacity, reasoning ability, or decision-making skill of women compared to men. Differences in anatomy do not translate into differences in cognitive ability. Nutrition and care during the prenatal and postnatal periods play a significant role in brain development, and when equal opportunities and resources are provided, women perform on par with men in every field.

History offers abundant proof: Kalpana Chawla (space science), Marie Curie (physics and chemistry), Sarojini Naidu (politics and literature), Indira Gandhi (politics), Margaret Thatcher (politics), Mother Teresa (humanitarian work), and Florence Nightingale (nursing and public health) all excelled at the highest levels, demonstrating that talent is not determined by gender.

Class 11 Physics Ch 1-Physical World Solutions – Question 1.14: Dirac’s “Beauty in Equations”

Criticize Dirac’s statement that beauty in equations matters more than agreement with experiment.

Answer:

Physics is fundamentally an experimental science — the ultimate test of any theory or equation is whether its predictions agree with observation and experiment. Elegance or simplicity alone cannot validate a physical law; a beautiful equation that fails to match experimental results must be rejected or revised. That said, many equations which have stood the test of experiment also happen to be remarkably simple and elegant — for example, Newton’s law of gravitation, Einstein’s mass-energy equivalence (E = mc²), and Maxwell’s equations of electromagnetism. When correctness and beauty coincide, it adds to our appreciation of the law, but beauty is never a substitute for experimental verification.

Question 1.15: Books by Great Physicists

Physicists such as Einstein, Bohr, Heisenberg, and Feynman have written about the simplicity and beauty of physical laws. Which books are worth reading?

Answer:

• Surely You’re Joking, Mr. Feynman! by Richard Feynman
• Physics for the Inquiring Mind by Eric M. Rogers
• Physics: Foundations and Frontiers by George Gamow and John M. Cleveland
• Thirty Years That Shook Physics by George Gamow
• Physics Can Be Fun by Yakov Perelman

Question 1.16: Scientists Have a Sense of Humor Too

Textbooks may give the impression that scientists are dry, humorless introverts. Is this true?

Answer:

This is entirely false — many celebrated scientists combined serious scientific achievement with a great sense of humor and enjoyment of life. C.V. Raman, for instance, was passionate about music alongside his groundbreaking scientific work, and Homi J. Bhabha was known for his deep appreciation of art and painting. Reading biographies and personal writings by scientists like Feynman and Gamow reveals the human, often playful side of scientific life.

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Class 11 Physics Ch 1-Physical World Solutions – Quick Self-Check Quiz

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