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PSEB 12th Class Chemistry Important Questions in Punjabi English Medium

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Punjab State Board Syllabus PSEB 12th Class Chemistry Important Questions Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 12.

PSEB 12th Class Chemistry Important Questions in Punjabi English Medium

PSEB 11th Class Geography Book Solutions Guide in Punjabi English Medium

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Punjab State Board Syllabus PSEB 11th Class Geography Book Solutions Guide Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 11.

PSEB 11th Class Geography Guide | Geography Guide for Class 11 PSEB

Geography Guide for Class 11 PSEB | PSEB 11th Class Geography Book Solutions

PSEB 11th Class Geography Book Solutions in Hindi Medium

Unit 1 सूर्यमण्डल

Unit 2 स्थलमण्डल

Unit 3 वायुमण्डल

Unit 4 जलमण्डल

PSEB 11th Class Geography प्रयोगात्मक भूगोल

PSEB 11th Class Geography Book Solutions in English Medium

Unit 1 Solar System

  • Chapter 1 The Earth
  • Chapter 2 Rocks
  • Chapter 3 Agents of Change : Denudation, Transportation and Deposition
  • Chapter 3(i) Denudation Works of River
  • Chapter 3(ii) Denudation Works of Glacier
  • Chapter 3(iii) Denudation Works of Winds
  • Chapter 3(iv) Denudation Works of Underground Water
  • Chapter 3(v) Denudation Works of Sea

Unit 2 Lithosphere

  • Chapter 4 Major Land Forms
  • Chapter 5 Volcanoes and Earthquakes
  • Chapter 5(i) Volcanoes
  • Chapter 5(ii) Earthquakes

Unit 3 Atmosphere

  • Chapter 6 Formation and Structure of Atmosphere
  • Chapter 7 Winds
  • Chapter 8 Humidity and Precipitation

Unit 4 Hydrospere

  • Chapter 9 The Ocean
  • Chapter 10 Geo-Political Significance of Indian Ocean

PSEB 11th Class Geography Practical Geography

  • Chapter 1 Maps
  • Chapter 2 Scale
  • Chapter 3 Enlargement and Reduction of Maps
  • Chapter 4 Topographical Maps
  • Chapter 5 Weather Maps
  • Chapter 6 Contours
  • Chapter 7 Weather Instrument

PSEB Class 11 Geography Structure of Question Paper

Class – XI (Pb.)
Geography

Time Allowed: 3 Hours
Theory: 70 Marks

The question paper has 5 sections comprising a total of 25 questions. All questions are compulsory.

Section – I
MCQ/Objective Type Questions: This section comprises questions with one word to one sentence answer/fill in the blanks/true or false etc. all multiple choice type questions. The section has 8 subparts (questions) 1 to 8, carrying one mark each. This section shall cover whole the syllabus. (1 × 8 = 8)

Section – II
Very Short Answer Type Questions: This section comprises questions of 7 subparts or questions 9 to 15, carrying 2 marks each. The answer to each question maybe two to three sentences. This section will cover whole the syllabus, choosing at least one question from each unit. (2 × 7 = 14)

Section – III
Short Answer Type Questions: This section comprises 5 subparts, questions 16 to 20, each carrying 4 marks. One question each from Unit I and Unit IV shall be set in this section and three questions from Unit II and Unit III. All the questions shall have an internal choice. (4 × 5 = 20)

Section – IV
Long Answer Type Questions: This section comprises of 3 subparts (questions) with 100% internal choice, 21 to 23, carrying 6 marks each. The answer to each question should be in about 100 to 150 words. All four Units of the Syllabus shall be covered. (6 × 3 = 18)

Section – V
Map Question: This section comprises two questions of map carrying 5 marks each. Students/Examinees are to attempt any 5 out of 8 items in each question. One part of map work pertains to identification and the other pertains to labelling in a political outline map of India and the World as per syllabus. (5 × 2 = 10)

Question Wise Break up

Type of Question Marks Per Question Total no. of Questions Total Marks Percentage
Objective Type (Learning checks) 1 8 8 11.5
Short Answer (VSA) 2 7 14 20
Short Answer (SA) 4 5 20 28.5
Long Answer (LA) 6 3 18 25.5
Map Skills Based 5 2 10 14.5
Total 25 70 100

Weightage to Content

Section A 8 Marks
Section B 14 Marks
Section C 20 Marks
Section D 18 Marks
Section E (Map Work) 10 Marks
Practical 20 Marks
Project Work/Book bank 8/2 Marks
Total 100 Marks

Weightage of Difficulty Level

Estimated Difficulty Level Percentage
Easy (E) 30%
Average (AV) 50%
Difficult (D) 20%

Design of Question Paper

Typology of questions MCQ/Objective Type (1 Mark) Very Short Answer (VSA)
(2 Marks)		 Short Answer-I (SA-I)
(4 Marks)		 Long Answer (LA) (6 Marks) Map Work (5) Total Marks % Wise Weightage
Remembering-
(Kno­wledge based Simple recall questions, to know specific facts, terms, concepts, principles or theories; Identity, defined or recite information)		 8 2 1 18 25.5%
Understanding- Comprehension-to be familiar with the meaning and to understand con­ceptually, interpret, compare, contrast, explain, paraphrase, or interpret information 3 3 2 30 43%
Application-
(Use abstract information in a concrete situation, to apply knowledge to the new situation; Use given content to interpret a situation, provide an example, or solve a problem)		 1 2 2 12 17%
Thinking Skills-
(Analysis & Synthesis classify, compare, contrast, or differentiate between different pieces of information, Organize  and/or integrate            unique pieces of information from a variety of sources)		 2 10 14.5%
Total – 70 8 7 × 2 = 14 5 × 4 = 20 3 × 6 = 18 2 × 5 = 10 Total = 70 100%

PSEB Class 11 Geography Syllabus

Theory

Unit – I: Solar System
Solar System: Earth Position of Earth in Solar System, Size and Shape, Movements of Earth and Effects, Longitudes and Latitudes.

Time; Local, Standard, and International Date Line.

Rocks: Origin, Classification, and Characteristics

Factors of change; Weathering and Denudation by river, glacier, wind, oceans, and underground water.

Unit – II: Lithosphere
Landforms: Mountains, Plateaus, and Plains; Origin, Classification and their significance to mankind.

Earthquakes: Causes, Effects, Types, and Distribution.

Volcanoes: Causes and effects of Volcanic activities.

Unit – III: Atmosphere

Extents, Layers, and composition.

Temperature; Factors controlling temperature, distribution, and range of temperature.

Pressures; Factors controlling pressures, horizontal and vertical distribution.

Winds; Planetary, seasonal and local; Shifting of wind belts and their impact. Cyclones and Anti-cyclones.

Humidity and Precipitation; Relative humidity and Specific humidity Precipitation types, rainfall types, and distribution.

Unit – IV: Hydrosphere
Oceans: Ocean basins and submarine relief, Ocean waters and their circulation, temperature, salinity^ waves, currents, and tides.

Special reference: Geopolitical importance of Indian Ocean.

Note:
A. Examples as far as possible be given from India.
B. Answers be illustrated with maps and diagrams.

Map Work: 20 Marks

Maps: Necessity of maps, classification, the scale of maps; R.F., Linear scale, its use in maps. Reduction and enlargement through the square method.

Direction: Finding direction in the field and on the map, Orientation of Local map in the field, methods of showing direction on the map.

Atlas map symbols: Identifications and Recognition of Symbols of conventional signs used in the atlas, Topographic sheet, and weather maps.

Methods of showing relief on maps: Contours, Interpolation of Contours identification of simple relief features from contours on a map.

Drawing of cross-section, observation, and recording of various weather elements with the help of the following instruments:
(a) Six’s minimum and maximum thermometer.
(b) Aneroid Barometer
(c) Wind Vane
(d) Wet and dry bulb thermometer
(e) Rain gauge
(f) Drawing of isotherms, isobars, and isohyets.

PSEB 12th Class Religion Book Solutions Guide in Punjabi English Medium

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Punjab State Board Syllabus PSEB 12th Class Religion Book Solutions Guide Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 12.

PSEB 12th Class Religion Guide | Religion Guide for Class 12 PSEB

PSEB 12th Class Religion Book Solutions in English Medium

Religion Guide for Class 12 PSEB | PSEB 12th Class Religion Book Solutions

PSEB 12th Class Religion Book Solutions in Punjabi Medium

Book Prescribed
An Introduction to Indian Religion by Harbans Singh & L.M. Joshi (Punjabi University, Patiala).

Book Suggested (for general reading)
Punjabi University, Patiala – Budhism, Jainism, Sikhism
Surinder Singh Johar – A hand book of Sikhism.

PSEB 12th Class Geography Book Solutions Guide in Punjabi English Medium

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Punjab State Board Syllabus PSEB 12th Class Geography Book Solutions Guide Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 12.

PSEB 12th Class Geography Guide | Geography Guide for Class 12 PSEB

Geography Guide for Class 12 PSEB | PSEB 12th Class Geography Book Solutions

PSEB 12th Class Geography Book Solutions in Hindi Medium

PSEB 12th Class Geography Book Solutions in English Medium

  • Chapter 1 Human Geography and its Branches
  • Chapter 2 Human Resources – Population and its Change
  • Chapter 3 Human Resources – Human Development and Settlements
  • Chapter 4 Economic Geography – Agriculture and Overview (Activities of Primary Sector)
  • Chapter 5 Economic Geography – Minerals and Energy Resources
  • Chapter 6 Economic Geography Manufacturing (Secondary Care and Knowledge/Activities of Specialised Areas
  • Chapter 7 Transport, Communication and Trade
  • Chapter 8 Geographical Perspective on selected Issues
  • Chapter 9 Practical Geography

PSEB 11th Class Agriculture Book Solutions Guide in Punjabi English Medium

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Punjab State Board Syllabus PSEB 11th Class Agriculture Book Solutions Guide Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 11.

PSEB 11th Class Agriculture Guide | Agriculture Guide for Class 11 PSEB in English Medium

Agriculture Guide for Class 11 PSEB | PSEB 11th Class Agriculture Book Solutions

PSEB 11th Class Agriculture Book Solutions in Hindi Medium

PSEB 12th Class Sociology Book Solutions Guide in Punjabi English Medium

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PSEB 12th Class Sociology Book Solutions

Punjab State Board Syllabus PSEB 12th Class Sociology Book Solutions Guide Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 12.

PSEB 12th Class Sociology Guide | Sociology Guide for Class 12 PSEB

Sociology Guide for Class 12 PSEB | PSEB 12th Class Sociology Book Solutions

PSEB 12th Class Sociology Book Solutions in English Medium

Unit 1 Tribal, Rural and Urban Society in India

Unit 2 Inequalities in Indian Society

Unit 3 Structural and Cultural Change in India

Unit 4 Social Problems in Indian Society

PSEB 12th Class Sociology Book Solutions in Hindi Medium

Unit-I भारत में जनजातीय, ग्रामीण तथा नगरीय समाज

Unit-II भारतीय समाज में असमानताएं

Unit-III भारत में संरचनात्मक तथा सांस्कृतिक परिवर्तन

Unit-IV भारतीय समाज में सामाजिक समस्याएं

PSEB 12th Class Sociology Syllabus

Unit I: Tribal, Rural and Urban Societies in India

1. Tribal Society: Meaning, Features; Classification of Tribes;
Marriage System; Issues- Deforestation and Displacement; Changes in Tribal Society.
2. Rural Society: Meaning, Features; Issues – Indebtedness, Impact of Green Revolution; Changes in Rural Society.
3. Urban Society: Meaning, Features; Issues of Housing and Slums.

Unit II: Inequalities in Indian Society

4. Caste Inequalities: Concept, Features; Caste and Social Stratification, Theories of Origin of Caste, Caste Inequality, and Indian Society.
5. Class Inequalities: Concept of class, Features of Class; Relations between caste, class, status Group and class Hierarchy, Views of Sociologists on class structure, Classes in Rural and Urban India.
6. Gender Inequalities: Concept, Gender Inequality, Theories of Feminism, Gender; Gender Discrimination: Meaning and Nature; Problems of Women, Role of Gender relation in Societal Development.

Unit III: Structural and Cultural Change in India

7. Westernisation and Sankritisation: Westernisation: Meaning, Carrier of process, Features, Impact: Sanskritisation: Meaning, Sanskritisation preferred as against Brahminisation, Dominant Caste, Impact.
8. Modernisation and Globalisation: Modernisation: Meaning, Characteristic, Process of Modernisation, Causes, Impact: Globalisation: Meaning, Characteristics, Process of globalization, Causes, Impact.
9. Social Movement: Meaning, Types, Stages, Caste Based Movements, Class-Based Movements, Women’s movements, environmental movements.

Unit IV: Social Problems in Indian Society

10. Social Problems: Alcoholism and Drug Addiction
11. Violence Against Women: Female Foeticide and Domestic Violence: Female Foeticide: Meaning, India Scenario, Causes, Consequences, Strategies to Combat Female Foeticide; Domestic Violence – Meaning, Forms, Factors, Causes, Effects, Remedies.
12. Social Issues: The Age and Disability: The Aged: Theories, Problems, Remedial Measures: Disability – Definition, Magnitude of Disability, Types, Causes, Social Model, Problems, Measures.

PSEB 5th Class Hindi Solutions Chapter 1 जब बोलो (कविता)

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Punjab State Board PSEB 5th Class Hindi Book Solutions Chapter 1 जब बोलो (कविता) Textbook Exercise Questions and Answers.

PSEB Solutions for Class 5 Hindi Chapter 1 जब बोलो (कविता) (2nd Language)

Hindi Guide for Class 5 PSEB जब बोलो Textbook Questions and Answers

जब बोलो (कविता) अभ्यास

नीचे गुरुमुखी और देवनागरी लिपि में दिये गये शब्दों को पढ़ो और हिंदी शब्दों को लिखने का अभ्यास करो-

  • भिमती = मिसरी
  • वप्ले = बोलो
  • मच = सच
  • भठ = मन

PSEB 5th Class Hindi Solutions Chapter 1 जब बोलो (कविता)

नीचे एक ही अर्थ के लिए पंजाबी और हिंदी भाषा में शब्द दिये गये हैं। इन्हें ध्यान से पढ़ो और हिंदी शब्दों को लिखो-

  • व = झुक
  • ताहां = गाँठें

सही शब्द चुनकर वाक्य पूरे करो

  1. हमें ………………………….. बोलना चाहिए। (रोकर/ हँसकर)
  2. हमारी बातचीत में ………………………….. होनी चाहिए। (मिठास/ कड़वाहट)
  3. हमें सदा ………………………….. बोलना चाहिए। (सच/ झूठ)
  4. हमें ………………………….. अपनी बात कहनी चाहिए। (जल्दी-जल्दी/ सोच-समझकर)
  5. हमें अपनी बात ………………………….. कहनी चाहिए। (अकड़कर/ झुककर)

उत्तर :

  1. हँसकर
  2. मिठास
  3. सच
  4. सोच – समझकर
  5. झुककर।

तुक मिलाओ

  1. जब = …………………………..
  2. सच = …………………………..
  3. झुक = …………………………..
  4. बोलो = …………………………..

उत्तर :

  1. जब – तब।
  2. सच – सच।
  3. झुक – रुक।
  4. बोलो – तोलो।

PSEB 5th Class Hindi Solutions Chapter 1 जब बोलो (कविता)

पढ़ो और समझो

  • हँस + कर = हँसकर
  • झुक + कर = झुककर
  • रुक + कर = रुककर
  • सोच + समझ + कर = सोच-समझकर

वाक्य बनाओ

  1. मिसरी-सी
  2. सच-सच
  3. रच-रच
  4. मन की गाँठें

उत्तर :

  1. मिसरी – सी – कोयल की मीठी कूक कानों में मिसरी – सी घोलती है।
  2. सच – सच – सच – सच बताओ, कल तुम कहाँ थे ?
  3. रच – रच – कभी न बातें रच – रच बोलो।
  4. मन की गाँठे – हँस – हँस कर अपने मन की गाँठे खोलो।

रचनात्मक अभिव्यक्ति
PSEB 5th Class Hindi Solutions Chapter 1 जब बोलो (कविता) 1
चित्र देखकर दिए गए शब्दों की सहायता से वाक्य पूरे करो-
आदर बुरी रोकर मिलजुलकर

  1. ऊँची आवाज़ में चीखकर बोलना ………………………….. आदत है।
  2. हमें आपस में ………………………….. रहना चाहिए।
  3. ………………………….. अपनी बात कहने वाले बच्चे किसी को नहीं भाते।
  4. हमें बड़ों का ………………………….. करना चाहिए।

उत्तर :

  1. बुरी
  2. मिल – जुलकर
  3. रोकर
  4. आदर।

PSEB 5th Class Hindi Solutions Chapter 1 जब बोलो (कविता)

बहुवैकल्पिक प्रश्न

प्रश्न 1.
‘बोलो’ की तुकबन्दी करते हुए शब्द मिलाएं, सही पर गोला लगाओ।
‘तोलो’ सुनो, बुलाओ, भलो
उत्तर :
तोलो

प्रश्न 2.
‘जब’ की तुकबन्दी करते हुए शब्द मिलाएं, सही पर गोला लगाओ।
तब, आब, साहब, ताब
उत्तर :
तब

प्रश्न 3.
‘सच’ की तुकबन्दी करते हुए शब्द मिलाएँ आज, राज, बच, बचना
उत्तर :
बच।

जब बोलो (कविता) Poems

1. जब बोलो, तब हँस कर बोलो,
बातों में मिसरी-सी घोलो।
जब बोलो, तब सच-सच बोलो,
कभी न बातें रच-रच बोलो।

शब्दार्थ –

मिसरी – सी = मिश्री जैसी, मिठास।
सच – सत्य।
रच – रच कर = बना – बना कर।

सरलार्थ – प्रस्तुत पंक्तियों में कवि बच्चों को वाणी में मधुरता और सत्यनिष्ठा को अपनाने की प्रेरणा देते हुए कहता है कि जब भी बोलो तब हँसहँस कर बात करो। मुस्कुरा कर बातें करनी चाहिएं ताकि सुनने वाले को अच्छा लगे। तुम्हारी बातों में मिठास होनी चाहिए। जब भी किसी से बात करो तो सच – सच बोलो कभी भी बना – बना कर बात नहीं करनी चाहिए।

PSEB 5th Class Hindi Solutions Chapter 1 जब बोलो (कविता)

2. जब बोलो, तब झुक कर बोलो,
सोच समझ कर, रुक कर बोलो।
हँस कर मन की गाँठे खोलो,
जब बोलो, तब हँस कर बोलो।

शब्दार्थ – झुककर = विनम्रता से। रुक कर = धीरे – धीरे, शांति से। हँस कर =मुस्करा कर। मन की गाँठें = मन के भेद।

सरलार्थ प्रस्तुत पंक्तियों में कवि बच्चों को विनम्रता और मधुरता को अपनाने की प्रेरणा देते हुए कहता है कि जब भी बोलो विनम्रता से बोलो, बात को सुन कर, सोच – समझकर और धीरे – धीरे, शांत भाव से बोलो। मन पर पडी दविधा की गाँठों को, परतों को, भेदों को, हँसकर खोलना चाहिए। मधुर वाणी बोलनी चाहिए। जब भी बोलो हँसकर बात करनी चाहिए।

जब बोलो (कविता) शब्दार्थ – Meanings

  • मिसरी = चीनी से बनी वस्तु
  • मिसरी-सी = मिठास से भरी हुई
  • रच-रच बोलना = अपने आप बात बनाकर कहना
  • मन की गाँठ = मन में छिपी बात

PSEB 12th Class Physics Important Questions in Punjabi English Medium

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Punjab State Board Syllabus PSEB 12th Class Physics Important Questions Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 12.

PSEB 12th Class Physics Important Questions in Punjabi English Medium

PSEB 12th Class Biology Important Questions in Punjabi English Medium

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Punjab State Board Syllabus PSEB 12th Class Biology Important Questions Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 12

PSEB 12th Class Biology Important Questions in Punjabi English Medium

PSEB 11th Class Physics Important Questions Chapter 1 Physical World

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Punjab State Board PSEB 11th Class Physics Important Questions Chapter 1 Physical World Important Questions and Answers.

PSEB 11th Class Physics Important Questions Chapter 1 Physical World

Very short answer type questions

Question 1.
Why do we call Physics an exact Science?
Answer:
Most of measurement in Physics are made with high precise and accuracy, so it is called an exact Science.

Question 2.
Give two approaches to study physics.
Answer:
Two approaches to study physics are unification and reduction.

Question 3.
Name the scientific principle behind the technology of steam engine.
Answer:
Laws of thermodynamics is the scientific principle behind the technology of steam engine.

PSEB 11th Class Physics Important Questions Chapter 1 Physical World

Question 4.
Give one major discovery resulted due to basic laws of electricity and magnetism.
Answer:
Wireless communication technology was a major discovery due to laws of electricity and magnetism.

Question 5.
What is the range of weak nuclear force?
Answer:
The range of a weak nuclear force is of the order of 10-16 m.

Question 6.
Give an example of achievement in unification.
Answer:
Unified celestial and terrestrial mechanics showed that the same laws of motion and the law of gravitation apply to both the domains.

Question 7.
Give an example for conservation law of energy.
Answer:
A freely falling body under gravity is an example of conservation law of energy.

Short answer type questions

Question 1.
Give the salient features of Einstein’s theory.
Answer:
According to Einstein

  • Mass and energy are interconvertible.
  • Space and time are interconnected.

Question 2.
Name the phenomena/fields with which microscopic domain of physics deals. Which theory explains these phenomena?
Answer:
The microscopic domain of physics deals with the constitution and structure of matter at atomic and nuclear scale.
The Questionuantum theory is currently accepted, as the proper framework for explaining microscopic phenomena.

PSEB 11th Class Physics Important Questions Chapter 1 Physical World

Question 3.
Name three important discoveries of physics, which have revolutionised modem chemistry.
Answer:
Three important discoveries of physics, which have revolutionised modem chemistry are :

  1. study of radioactivity,
  2. quantum theory
  3. study of isotopes and determination of their masses by mass spectrographs.

Question 4.
Name four fundamental forces in nature.
Answer:
Four fundamental forces present in nature are:

  • Gravitational force
  • Electromagnetic force
  • Weak nuclear force
  • Strong nuclear force.

Question 5.
Name three important discoveries of physics, which have contributed a lot in development of biological sciences.
Answer:
The most important discoveries of physics, which have contributed a lot in development of biological sciences are :

  • Ultrasonic waves.
  • X-rays and neutron diffraction technique.
  • Electron microscope.
  • Radio isotopes.

Question 6.
Briefly explain how physics is related to technology?
Answer:
Progress in the field of science and technology is interrelated. Sometimes technology gives rise to new physics and at other times physics generates new technology. The discipline of thermodynamics arose mainly to understand and improve the working of heat engines. Similarly discovery of basic laws of electricity and magnetism led to development of wireless communication technology. Therefore, we can conclude that physics and technology are closely related.

Long answer type questions

Question 1.
How Physics is related to other sciences?
Answer:
Physics is so important branch of science that without the knowledge of Physics, other branches of science cannot make any progress. This can be seen from the following:

(a) Physics in relation to Mathematics: The theories and concepts of Physics lead to the development of various mathematical tools like differential equations, equations of motion etc.

(b) Physics in relation to Chemistry: The concept of interaction between various particles lead to understand the bonding and the chemical structure of a substance. The concept of X-ray diffraction and radioactivity had helped to distinguish between the various solids and to modify the periodic table.

(c) Physics in relation to Biology: The concept of pressure and its measurement has helped us to know the blood pressure of a human being, which in turn is helpful to know the working of heart. The discovery of X-rays has made it possible to diagonose the various diseases in the body and fracture in bones. The optical and electron microscopes are helpful in the studies of various organisms. Skin diseases and cancer can be cured with the help of high energy radiations like X-rays, ultraviolet rays.

(d) Physics in relation to Geology: The internal structure of various rocks can be known with the study of crystal structure. Age of rocks and fossils can be known easily with the help of radioactivity i. e., with the help of carbon dating.

(e) Physics in relation to Astronomy: Optical telescope has made it possible to study the motion of various planets and satellites in our solar system.
Radio telescope has helped to study the structure of our galaxy and to discover pulsars and quasars (heavenly bodies having star like structure). Pulsars are rapidly rotating neutron stars. Doppler’s effect predicted the expAnswer:ion of universe. Kepler’s laws are responsible to understand the nature of orbits of the planets around the sun.

(f) Physics in relation of Meterology: The variation of pressure with temperature leads to forecast the weather.

(g) Physics in relation to Seismology: The movement of earth’s crust and the types of waves produced help us in studying the earthquake and its effect.

PSEB 11th Class Physics Important Questions Chapter 1 Physical World

Question 2.
Write short note on origin and Fundamental forces in nature.
Answer:
These are the. following four basic forces in nature:
(a) Gravitational forces
(b) Electromagnetic forces
(c) Strong force or nuclear forces
(d) Weak forces.
Some of the important features of these forces are discussed below:

(a) Gravitational forces: These are the forces of attraction between any two bodies in the universe due to their masses separated by a definite distance. These are governed by Newton’s law of gravitation given by
PSEB 11th Class Physics Important Questions Chapter 1 Physical World 1
where, m1, m2 are the masses of two bodies
r = distance between them
G = Universal gravitational constant
= 6.67 × 1011 Nm2kg2

Characteristics of Gravitational Forces

  • They are always attractive. They are never repulsive. They exist between macroscopic as well as microscopic bodies.
  • They are the weakest forces in nature.
  • They are central forces in nature i. e., they set along the line joining the centres of two bodies.
  • They are conservative forces.
  • They obey inverse square law i.e.,F ∝ \(\frac{I}{r^{2}}\) they vary inversely as the
    square of the distance between the two bodies.
  • They are long range forces i.e., gravitational forces between any two bodies exist even when their distance of separatioji is quite large.
  • The field particles of gravitational forces are called gravions. The concept of exchange of field particles between two bodies explains how the two bodies interact from a distance.

(b) Electromagnetic forces: They include the electrostatic and magnetic forces. The electrostatic forces are the forces between two static charges while magnetic forces are the forces between two magnetic poles. The moving charges give rise to the magnetic firce. The combined action of these forces are called electromagnetic forces.
Characteristics of Electromagnetic Forces

  • These forces are both attractive as well as repulsive.
  • They are central forces in anture.
  • They obey inverse sQuestionuare law.
  • They are conservative forces in nature.
  • These forces are due to the exchange of particles known as photons which carry no charge and have zero rest mass.
  • They are 10 times stronger as compared to gravitational forces and 1011 times stronger than the weak forces.

(c) Strong forces: They are the forces of nuclear origin. The particles inside the nucleus are charged particles (protons) and neutral particles (neutrons) which are bonded to each other by a strong interaction called nuclear force or strong force.
Hence they may be defined as the forces binding the nucleons (protons and neutrons) together in a nucleus. They are responsible for the stability of the atomic nucleus. They are of three types :

  1. n-n forces are the forces of attraction between two neutrons.
  2. p-p forces are the forces of attraction between two protons.
  3. n-p forces are the forces of attraction between a proton and a neutron.

Characteristics of Strong Forces

  • They are basically attractive in nature and become repulsive when the distance between nucleons is less than 0.7 fermi.
  • They obey inverse square law.

(d) Weak forces: They are defined as the interactions which take place between elementary particles during radioactive decay of a radioactive substance. In β – decay, the nucleus changes into a proton, an electron and a particle called anti-neutrino (which is uncharged). The interaction between the electron and the anti-neutrino is known as weak interaction or weak force.

Characteristics of Weak Forces

  • They are 1025 times stronger than the gravitational forces.
  • They exist between leptons and leptons, leptons and mesons etc.
    (a) and (b) types are the forces that we encouncer in macroscopic world while (c) and (d) types are the forces that we encountered in microscopic world.