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Physical World

Class 11th Physics Part I CBSE Solution

Exercise
Question 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 complexity content of this world is very high. Almost everything in this world is equated in terms of mass, time and length. In spite of all this, all the physical phenomena can be explained with very few basic principles of Physics. So basically, Einstein meant to say that despite such complexities, it is possible to simplify the world with some basic laws of Physics.



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:

There are two sides of Physics, one which is orthodox and goes by convention like for example negative or positive signs assigned to the values and the other, which is the one which does not follow conventions. Now, the opinions which are against the conventions are called HERESY, while an established stuff is known as DOGMA. For example, Copernicus’s geocentric theory was a heresy, until it was proved and became a Dogma.



Question 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:

Politics is a dirty game. You play in a dirty game, sweep it under the carpet, no one notices it and you remain in power. That is what the politicians do, they try to remain in power by any illegal or foul methods and never follow the norms. Meanwhile, a scientist gives times to phenomena, observes it carefully study it, explain it to the whole world and after a discovery is confirmed they present it to the whole world for its own good sake. This is why “Politics is the art of possible” and “Science is the art of soluble”.



Question 4.

Though India now has a large base in science and technology, which is fast expanding, it is still a long way from realising its potential of becoming a world leader in science. Name some important factors, which in your view have hindered the advancement of science in India.


Answer:

Factors which have hindered the advancement of science in India are as follows:-


1. Lack of clear-cut policies at the political level. Undue political interference and bureaucratization in the management of science and technology.


2. Due to excessive population, our country cannot afford to expend sufficient funds on science and technology.


3. Gifted scientists and researchers are not given proper exposure. They should be encouraged to do more of research work from a little age.


4. There is lack of coordination between researchers and


industrialists. Industrialists like to borrow technology from advanced countries rather than to use indigenous technology.



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:

Theorems existing in this world are all based on the fact that electrons do exist in atoms. If the concept of the electron is removed from proven Physics, then there will be a crisis of arguments in the existing theories and anything won’t be enough to correctly explain the theories. Whereas, removing ghosts from the world won’t affect any of the existing concepts.



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 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 course of time the shape was genetically propagated. This is an example of evolution by artificial selection.

[Note: This interesting illustration is taken from Carl Sagan’s ‘The Cosmos’ highlights the 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:

Option B is the best explanation.


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 course of time the shape was genetically propagated. This is an example of evolution by artificial selection.


Explanation: Nature won’t give tribute to anyone. It is governed by the laws of physics. But, there is a chance of formation of samurai's face accidentally by means of probability.



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:

The industrial revolution starts in England and Western Europe in mid-18th Century. Its main contributions are inventions to perform work in effective and efficient manner. Some of them are,


1. Blast Furnace


It is the closed type of furnace which is capable of generating high temperatures. It is used to convert Iron into steel which is most widely used element nowadays.


2. Cotton Jenney


It is said to be a most valuable invention in the 18th century because it reduces time to collect cotton from cotton flowers. It is almost 300 times efficient than a normal hand.


3. Steam engine


Steam engine invented by James Watt. It revolutionizes the transport system which ultimately leads to connectivity between countries. So, different peoples, cultures and their ideas mingle to form revolutionary products and inventions to the modern world.



Fig. Steam Engine James Watt_1784


There are many other inventions that are outcomes of the industrial revolution which pave the path for modern technology.



Question 8.

It is often said 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:

The major areas which will lead to second Industrial revolution in future are,


1. Internet and its availability to users


2. Development of supercomputers


3. Development of superconductors


4. Artificial Intelligence and machine learning


5. Exploration of universe


6. DNA as a source of data storage, etc.



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:

Let me take into the year A.D 2125. Human colonies are developed on mars and moon. One day evening a mysterious asteroid driven by aliens coming towards our colonies, then International Space Soldiers Army (ISSA) which is developed by all the nations have come into the picture. They pointed a multi satellite-based Laser gun (MSLG) towards it and destroyed the asteroid. This MSLG is working with the radiation coming from the sun, it has debris collector inbuilt and it requires no other source of energy.



Question 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:

There are still so many hidden secrets in the universe. A discovery or invention cannot be hidden under the mask because man seeks progress. His enthusiasm leads to discoveries and inventions. It’s me or other, whoever may be every governing law of nature will be revealed. As a coin has two sides, knowledge too. It helps in the understanding of nature but also may cause harm. A wise knowledgeable person never hesitates to reveal his work to society.


But, the one who is using that knowledge have two options,


CONSTRUCTION or DESTRUCTION it depends one's perspective thinking and wisdom.



Question 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 categorized:

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 the 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. The small pox virus kills so many human beings and survivors have permanent effects. Thus, the mass vaccination against smallpox is good for society.


B. Television for the eradication of literacy and for mass communication of news and ideas is good.


C. Parental sex determination is considered to be bad because it leads to gender imbalance and it is banned legally in many countries.


D. Computers are helpful to do a work in an efficient manner and in an effective way. It results in globalization and increases connectivity between people around the world. Thus, Computers are considered to be good.


E. Launching of artificial satellites is good because the internet, television, a Global positioning system (GPS) and many other bridges between human across the great seas are based on this artificial satellite.


F. Even though Development of nuclear physics leads to effective generations of electricity it is considered to be bad. Because, it gives rise to the destruction of human colonies during wars, insert permanent changes to genes of living beings and cause environmental changes.


G. Development of new and powerful techniques of chemical and biological warfare is bad. It can be simply misused by terrorists, anti-government societies, etc.


H. Purification of Drinking water is good. It is the main problem that we are facing nowadays.


I. Plastic surgery is considered to be good. Because, it gives new life to victims of acid drop, fire accidents, and many others.


J. Cloning is cannot be categorized. Because, reproduction of new organs using cloning is good but, production of whole human being leads to so many social and security problems.



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 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:

First and foremost, step would be to educate the people and spread the literacy. The people must be taught about the science behind the natural phenomenon occurring in nature day-to-day life and superstitious beliefs, these phenomena which people attribute to evil spirits and gods should be explained scientifically through mass media such as television, newspapers, cinema, etc. we also should not take these superstitions for granted and follow them. Instead, we should do otherwise. We should also tell and try to convince other people to not to believe or follow the superstitions unless they are scientifically proven. We should investigate these superstitions to its roots, if possible.



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:

The names of Madame Curie the Nobel laureate, Indira Gandhi, Margaret Thatcher, Mother Teresa, Kalpana Chawla, from various fields varying from science to sociology is very well-known to the world, and at times these need to be reminded of the people who hold unscientific views on a woman’s innate nature, capacity and intelligence, and in practice give them a secondary status and role. By nature, there exists some difference in man and woman biologically, but that doesn’t make women any inferior to men.



Question 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:

An equation strikes to someone as beautiful if it’s essence is understood to him/her. Some of the beautiful equations from this book are Newton’s 2nd Law of motion (i.e. F = ma), Einstein’s Equation for mass-energy relation (E = mc2).There are some equations of Quantum Mechanics and Theory of Relativity are highly cumbersome and difficult to understand, yet they agree with the experiments.



Question 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:

Books on General Physics are interesting, like ‘Surely you are joking, Mr. Feynman’ by Richard Feynman is one of the books. Interested students should consult their teachers and should go to the library and search these books. Students can search for these books on the internet as well.



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 humourists, 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:

Scientists, like any other group of humans, have their share of humourists, and many have led their lives with a great sense of fun and adventure, even as they seriously pursued their scientific work. We can take the example of many scientists like Albert Einstein, Richard Feynman. C.V. Raman, etc., who were fun, adventurists and loving. Albert Einstein played the violin and enjoyed Mozart’s music, Richard Feynman the greatest explainer ever was humours and he played the bongo in addition to doing the serious scientific work.