Important MCQ 10th CBSE : LIFE PROCESS

 

For more Click here Path Finder Class 8th to 12th

chapter electricity full chapter

Important Guess Questions For Bihar Board Class 12th MATH 2021

IMPORTANT QUESTIONS FOR BIHAR BOARD CLASS 12TH MATHS 2021

Best Notes of Arithmetic progression#AP and Geometric Progression#GP #Class11#maths#CBSE#BIHARBOARD#pathfinder#SurajSir

Notes of AP & GP

ARITHMETIC PROGRESSION

GEOMETRIC PROGRESSION

Important Question Of Combustion and Flame #class8 #Important #Questions #Internal CBSE #PATHFINDER

These Internal Questions are Very Important for students

COMBUSTION AND FLAME

कुछ लोग हमेशा परिस्थितियों को ही दोष देते है ; Motivational story in hindi

 कुछ लोग हमेशा परिस्थितियों  को ही दोष देते है

यह motivational story ऐसी है
जिसको सुनकर आपकी आंखें खुल सकती है
इस कहानी को जल्दी से जल्दी  शुरू करते हैं

काफी समय पहले की बात है दोस्तों
एक आदमी रेगिस्तान में फंस गया था 

वह मन ही मन अपने आप को बोल रहा था कि यह कितनी अच्छी और सुंदर जगह है

अगर यहां पर पानी होता तो यहां पर कितने अच्छे-अच्छे पेड़ उग रहे होते 

और यहां पर कितने लोग घूमने आना चाहते होंगे
 मतलब ब्लेम कर रहा था

 कि यह होता तो वो होता  और वो होता  तो शायद ऐसा होता 

ऊपरवाला देख रहा था अब उस इंसान ने सोचा यहां पर पानी नहीं दिख रहा है 

उसको थोड़ी देर आगे जाने के बाद उसको एक कुआं दिखाई दिया जो कि

 पानी से लबालब भरा हुआ था काफी देर तक
 विचार-विमर्श करता रहा खुद से

 फिर बाद उसको वहां पर एक रस्सी और बाल्टी  दिखाई दी  इसके बाद कहीं से
एक पर्ची उड़ के आती है जिस पर्ची में लिखा हुआ था कि तुमने कहा था कि
यहां पर पानी का कोई स्त्रोत  नहीं है अब तुम्हारे पास पानी का स्रोत भी है
अगर तुम चाहते हो तो यहां पर पौधे लगा सकते हो
वह चला गया दोस्तों
 तो यह कहानी हमें क्या सिखाती है
यह कहानी हमें यह सिखाती है कि
अगर आप परिस्थितियों को दोष देना चाहते हो कोई दिक्कत नहीं है
 लेकिन आप परिस्थितियों को दोष देते हो कि अगर यहां पर ऐसा  हो और
आपको वह सोर्सेस मिल जाए तो क्या परिस्थिति को बदल सकते हो

 इस कहानी में तो यही लगता है कि कुछ लोग सिर्फ परिस्थिति को दोष देना जानते हैं
अगर उनके पास उपयुक्त स्रोत हो तो वह परिस्थिति को नहीं बदल सकते
सिर्फ वह ब्लेम करना जानते हैं लेकिन हमे ऐसा  नहीं बनना है दोस्तों
 इस कहानी से यह शिक्षा मिलती है कि अगर आप चाहते हो कि
 परिस्थितियां बदले और आपको अगर उसके लिए उपयुक्त साधन मिल जाए तो
आप अपना एक परसेंट योगदान तो दे ही सकते हैं और
मुझे पूरा भरोसा है कि अगर  आपके साथ ऐसी कोई घटना घटित होती है
आप अपना योगदान जरूर देंगे
यह कहानी आपको अच्छी लगी होगी अगर आप चाहते हो कि
 आपको ऐसी मजेदार कहानियां मिलती रहे तो आप बिल्कुल सही जगह पर है

दोस्तों मेने आपका ज्यादा समय  खराब नहीं किया और इस motivational story को मैंने कम से कम
 शब्दों में समेटने  की कोशिश की है जो कि मैं कर पाया अगर आपके
 कोई सुझाव हो तो कमेंट के माध्यम से मुझे जरूर बताएं और अगर
आपको यह motivational story अच्छी लगी हो तो इस कहानी को और लोगों से
आपके दोस्तों के साथ आप शेयर करिए
 शुक्रिया

Conservation Of Plants And Animals Class 8 Notes/pathfinder/suraj sir

 

Conservation Of Plants And Animals Class 8 Notes

Extinction

• Extinction is when a species is completely wiped out from Earth.
• Once the last living individual of a species dies, the species is said to be extinct.

Deforestation

• Deforestation is the destruction of forests by cutting down trees.
• Deforestation leads to habitat loss for many animals.

Causes of deforestation

Deforestation can occur due to one of the following reasons:

• Procuring land for cultivation.
• Building houses and factories.
• Making furniture or using wood as fuel.
• Natural causes such as forest fire and severe drought can also cause deforestation.

Consequences of deforestation

• Deforestation increases the temperature and pollution level on the earth.
• It increases the level of carbon dioxide in the atmosphere.
• It also reduces the level of groundwater.

Droughts

• Drought is the lack of water in an area. Droughts can happen due to lack of rainfall.

Desertification

• Formation of a desert by erosion of vegetation due to harsh weather is called desertification.
• Human activities like deforestation and improper irrigation are also responsible for desertification of terrains.

Global Warming

• Global warming is the change of climate on a global level.
• Usually, average temperature increases leading to melting of ice caps in the poles.
• Excessive pollution and deforestation cause global warming.

Species

• A species is a group of individuals that can breed and successfully produce fertile offsprings.

Make the World a Greener Place

Recycling of Paper

• Paper industry is a leading cause of deforestation since they need wood pulp.
• Recycling paper can help in reducing the consumption of wood pulp by the paper industry.

Reforestation

• Reforestation is restocking of the destroyed forests by planting new trees.

Wildlife Conservation

Conservation of forest and wildlife

• Due to the threat from mankind’s indulgence, it is important for us to conserve the forest and its wildlife.
• Wildlife is important for us to maintain balance in nature.

Wildlife sanctuary

• A wildlife sanctuary, is a naturally occurring sanctuary, such as an island, that provides protection for species from hunting, predation, competition or poaching.

National Park

Flora and fauna

• The plants and animals found in a particular area are termed flora and fauna of that area respectively.

National Park

• A national park is a park that is used for biodiversity conservation.
• They are developed and maintained by the union government.

Biosphere Reserves

Biosphere and Biodiversity

• The biosphere is that part of the earth in which living organisms exist or which supports life.
• Biological diversity or biodiversity refers to the variety of organisms existing on the earth, their interrelationships and their relationship with the environment.

Endemic species

• Endemic species are those species of plants and animals which are found exclusively in a particular area.

Biosphere reserve

• Biosphere reserves are areas that protected from human intervention.
• These areas help in conservation of endangered species.

Project Tiger

• Project Tiger was launched by the government to protect and conserve the dwindling tiger population in the country.
• Several Natural parks have been associated with the project tiger initiative.

Endangered animals

• Animals whose numbers are diminishing to a level that they might face extinction are known as endangered animals.

Ecosystem

• An ecosystem is sum total of all the plants, animals and microorganisms in an area along with non-living components such as climate, soil, river deltas, etc.

Red Data Book

Red Data Book is the source book which keeps a record of all the endangered animals and plants.

Migration

• Migration is the periodic movement of animals from one place to another.
• It is usually done for breeding and to escape harsh climates.
• Migration is common in birds and fishes.

Magnetic Effects of Electric Current Class 10 Notes Class 10 Science Chapter 13/by path finder/suraj sir

 

Magnetic Effects of Electric Current Class 10 Notes

Class 10 Science Chapter 13 Magnetic Effects Of Electric Notes: 

CLICH HERE TO WATCH VIDEOS ON OUR YOUTUBE CHANNEL

https://youtu.be/WpFxcJsOxvc

Field and Field Lines

Magnet

A magnet is a material that produces a field that attracts or repels other such materials of magnetic nature.
Lodestone is a naturally occurring magnet. It attracts materials like Iron, Nickel, Cobalt, etc.

North and South Poles

A magnet is always bipolar with poles named north and south poles. These two poles always exist together and can not be separated. North pole of a magnet is the side which points to Earth’s geographic north when it is freely suspended.

Like poles repel and unlike poles attract

Similar to charges, poles attract and repel. Like poles repel while unlike poles attract each other.

Bar magnet

A bar magnet is a rectangular object, composed of iron, steel or any form of a ferromagnetic substance, that shows permanent magnetic properties. It has two different poles, a north and a south pole such that when suspended freely, the north pole aligns itself towards the geographic north pole of the Earth.

Magnetic field

The region around a magnet where its magnetic influence can be experienced is called a magnetic field. The direction and strength of a magnetic field are represented by magnetic lines of force.

For More Information On Magnetic Field and Magnet Field Lines, Watch The Below Video:

76,564

Iron filings test around a bar magnet

Iron filings around a bar magnet exhibit the magnetic field lines that engirdle the bar magnet. The magnetic field lines can be explained as imaginary lines that graphically represents the magnetic field that is acting around any magnetic substance.

Magnetic field lines

• Magnet’s magnetic field lines result in the formation of continuous/running closed loops.
• The tangent to the field line at any given point indicates the direction of the total magnetic field at that point.
• The greater the number of field lines crossing per unit area, the higher the intensity, the stronger the magnitude of the magnetic field.
• There is no intersection between the magnetic field lines.

Magnetic field lines for a closed loop

Since magnets have dipoles, magnetic field lines must originate and end. Therefore by convention, it starts at the north pole and moves towards the south pole outside the bar magnet and from south $\to$ north inside the magnet. Hence, it forms closed loops.

No two magnetic field lines intersect

Magnetic field lines do not intersect as there will be two tangential magnetic field directions associated with the same point, which does not occur. If a compass needle is placed at that point, it will show two different directions of the magnetic field which is absurd.

Relative strength of magnetic field inferred from magnetic field lines

The closer or denser the magnetic field lines, greater is the magnetic field’s strength.

Magnetic Field Due to a Current Carrying Conductor

Oersted’s experiment

When electric current flows through a current carrying conductor, it produces a magnetic field around it. This can be seen with the help of a magnetic needle which shows deflection. The more the current, the higher the deflection. If the direction of current is reversed, the direction of deflection is also reversed.

Electromagnetism and electromagnet

An electromagnet is an artificial magnet which produces a magnetic field on the passage of electric current through a conductor. This field disappears when the current is turned off. The phenomenon of producing or inducing a magnetic field due to the passage of electric current is called electromagnetism.

For More Information On Introduction to Electromagnetism, Watch The Below Video:

94,856

Magnetic field due to a straight current carrying conductor

When current is passed through a straight current-carrying conductor, a magnetic field is produced around it. Using the iron filings, we can observe that they align themselves in concentric circles around the conductor.

Right-hand thumb rule

If a straight conductor is held in the right hand in such a way that the thumb points along the direction of the current, then the tips of the fingers or the curl of the fingers show the direction of magnetic field around it.

Magnetic field due to current through a circular loop

The right-hand thumb rule can be used for a circular conducting wire as well as it comprises of small straight segments. Every point on the wire carrying current gives rise to a magnetic field that appears as straight lines at the centre.

Magnetic field due to current in a solenoid

A solenoid is a coil of many circular windings wrapped in the shape of a cylinder. When current is passed through it, it behaves similar to a bar magnet, producing a very similar field pattern as that of a bar magnet. To increase the strength a soft iron core is used.

Force on a Current Carrying Conductor in a Magnetic Field

Ampere’s experiment

When an electric conductor is placed in a magnetic field, it experiences a force. This force is directly proportional to the current and is also perpendicular to its length and magnetic field.

​​​​Force on a straight current carrying conductor placed in a magnetic field

Force on a straight current carrying conductor is mutually perpendicular to the magnetic field and the direction of the current.

Fleming’s left-hand rule

Fleming’s left hand rule states that the direction of force applied to a current carrying wire is perpendicular to both, the direction of current as well as the magnetic field.

Electric motor

Electric Motor converts electrical energy into mechanical energy.

• Current enters arm AB through brush X and current flows through brush Y from C to D. Using Fleming’s LHR we find that the force pushes AB downwards and pushes CD upwards.
• In an electric motor the split rings PQ act as a commutator that reverses the direction of the current. The reversing of the current is repeated at each half rotation, giving rise to a continuous rotation of the coil.

Electromagnetic Induction and Electric Generators

Faraday’s experiment

• Faraday discovered that a magnetic field interacts with an electric circuit by inducing a voltage known as EMF (electromotive force) by electromagnetic induction.
• Moving a magnet towards a coil sets up a current in the coil circuit, as indicated by deflection in the galvanometer needle.

Electromagnetic induction

The phenomenon of electromagnetic induction is the production of induced EMF and thereby current in a coil, due to the varying magnetic field with time. If a coil is placed near a current-carrying conductor, the magnetic field changes due to a change in I or due to the relative motion between the coil and conductor. The direction of the induced current is given by Fleming’s right-hand rule.

Fleming’s right-hand rule

According to Fleming’s right-hand rule, the thumb, forefinger and middle finger of the right hand are stretched to be perpendicular to each other as indicated below. If the thumb indicates the direction of the movement of conductor, fore-finger indicating direction of the magnetic field, then the middle finger indicates direction of the induced current.

Electric generator

• The device that converts mechanical energy into electrical energy.
• Operates on the principle of electromagnetic induction.
• AC Generation: The axle attached to the two rings is rotated so that the arms AB and CD move up and down respectively in the produced magnetic field. Thus, the induced current flows through ABCD.

• After half rotation the direction of current in both arms changes. Again by applying Fleming’s right hand rule, the induced currents are established in these arms along directions DC and BA, therefore the induced I flows through DCBA.
• DC Generation: They work just like AC, instead use half rings to produce current in one direction only without variations in magnitude.

Domestic Electric Circuits

Fuse

• Fuse is a protective device in an electrical circuit in times of overloading.
• Overloading is caused when the neutral and live wire come in contact due to damage to the insulation or a fault in the line.
• In times of overloading the current in circuit increases (short circuit) and becomes hazardous. Joule’s heating (resistive or ohmic heating on the passage of current) in the fuse device melts the circuit and breaks the flow of current in the circuit.

 

Domestic electric circuits

• Livewire has a voltage of 220 V and is covered with red insulation.
• Earth wire has a voltage of 0 V (same as Earth) and is covered with green insulation.
• The neutral wire has black insulation.
• In our houses, we receive AC electric power of 220 V with a frequency of 50 Hz.

Power loss in transmission

Power losses in transmission lines over long distances occur due to Joule’s heating. This heat $\left(H\right)\propto l^{2}R$ causes losses where R is the line resistance.

Mid point theorem class 9 /class 10/very easy explanation/in hindi/maths...

Notes of chemical reaction and equation class 10 cbse/by path finder/suraj sir

 

Introduction to Chemical Reactions and Equations

by path finder coaching

join us on youtube  click here

Physical and chemical changes

Chemical change – one or more new substances with new physical and chemical properties are formed.

Here, when copper sulphate reacts with iron, two new substances, i.e., ferrous sulphate and copper are formed.

Physical change – change in colour or state occurs but no new substance is formed.
Example: Water changes to steam on boiling but no new substance is formed(Even though steam and water look different when they are made to react with a piece of Na, they react the same way and give the exact same products). This involves only a change in state (liquid to vapour).

Observations that help determine a chemical reaction

A chemical reaction can be determined with the help of any of the following observations:
a) Evolution of a gas
b) Change in temperature
c) Formation of a precipitate
d) Change in colour
e) Change of state

Chemical reaction

Chemical reactions are chemical changes in which reactants transform into products by making or breaking of bonds (or both) between different atoms.

Types of chemical reactions

Taking into consideration different factors, chemical reactions are grouped into multiple categories.
Few examples are:
● Combination
● Decomposition
● Single Displacement
● Double displacement
● Redox
● Endothermic
● Exothermic
● Precipitation
● Neutralisation

Chemical Reactions and Equations I

Word equation

A  word equation is a chemical reaction expressed in words rather than chemical formulas. It helps identify the reactants and products in a chemical reaction.
For example,
Sodium + Chlorine → Sodium chloride
The above equation means: “Sodium reacts with chlorine to form sodium chloride.”

Symbols of elements and their valencies

A symbol is the chemical code for an element. Each element has one or two-letter atomic symbol, which is the abbreviated form of its name.
Valency is the combining capacity of an element. It can be considered as the number of electrons lost, gain or shared by an atom when it combines with another atom to form a molecule.

Writing chemical equations

Representation of a chemical reaction in terms of symbols and chemical formulae of the reactants and products is known as a chemical equation.

• For solids, the symbol is “(s)”.
• For liquids, it is “(l)”.
• For gases, it is “(g)”.
• For aqueous solutions, it is “(aq)”.
• For gas produced in the reaction, it is represented by “(↑)”.
• For precipitate formed in the reaction, it is represented by “(↓)”.

Balancing of a Chemical Reaction

Conservation of mass

According to the law of conservation of mass, no atoms can be created or destroyed in a chemical reaction, so the number of atoms for each element in the reactants side has to balance the number of atoms that are present in the products side.
In other words, the total mass of the products formed in a chemical reaction is equal to the total mass of the reactants participated in a chemical reaction.

Balanced chemical equation

The chemical equation in which the number of atoms of each element in the reactants side is equal to that of the products side is called a balanced chemical equation.

Steps for balancing chemical equations

Hit and trial method: While balancing the equation, change the coefficients (the numbers in front of the compound or molecule) so that the number of atoms of each element is same on each side of the chemical equation.

Short-cut technique for balancing a chemical equation

Example:

aCaCO3 + bH3PO4 → cCa3(PO4)2 + dH2CO3

Set up a series of simultaneous equations, one for each element.

Ca: a=3c

C: a=d

O: 3a+4b=8c+3d

H: 3b=2d

P: b=2c

Let’s set c=1

Then a=3 and

d = a = 3

b = 2c = 2

So a=3; b=2; c=1; d=3

The balanced equation is

3CaCO3 + 2H3PO4 → Ca3 (PO4)2 + 3H2CO3

Chemical Reactions and Equations II

Types of chemical reactions

Taking into consideration different factors, chemical reactions are grouped into multiple categories.
Few examples are:
● Combination
● Decomposition
● Single Displacement
● Double displacement
● Redox
● Endothermic
● Exothermic
● Precipitation
● Neutralisation

Combination reaction

In a combination reaction, two elements or one element and one compound or two compounds combine to give one single product.

Decomposition reaction

A single reactant decomposes on the application of heat or light or electricity to give two or more products.
Types of decomposition reactions:
a. Decomposition reactions which require heat – thermolytic decomposition or thermolysis.

                                               Thermal decomposition of HgO

b. Decomposition reactions which require light – photolytic decomposition or photolysis.

                                       Photolytic decomposition of $H_2{O}_2$

c. Decomposition reactions which require electricity – electrolytic decomposition or electrolysis.

 

Electrolytic decomposition of $H_{2}O$

Displacement reaction

More reactive element displaces a less reactive element from its compound or solution.

Double displacement reaction

An exchange of ions between the reactants takes place to give new products.
For example, 

Precipitation reaction

An insoluble compound called precipitate forms when two solutions containing soluble salts are combined.

Redox reaction

Oxidation and reduction take place simultaneously.
Oxidation: Substance loses electrons or gains oxygen or loses hydrogen.
Reduction: Substance gains electrons or loses oxygen or gains hydrogen.
Oxidising agent – a substance that oxidises another substance and self-gets reduced.
Reducing agent – a substance that reduces another substance and self-gets oxidised.

Endothermic and exothermic reaction

Exothermic reaction – heat is evolved during a reaction. Most of the combination reactions are exothermic.

Al + Fe2O3 → Al2O3 + Fe + heat
CH4 + 2O2 → CO2 + 2H2O + heat

Endothermic – Heat is required to carry out the reaction.

6CO2 + 6H2O + Sunlight → C6H12O6 + 6O2

Glucose
Most of the decomposition reactions are endothermic.

Corrosion

Gradual deterioration of a material, usually a metal, by the action of moisture, air or chemicals in the surrounding environment.

Rusting:

 4Fe(s) + 3O2(from air) + xH2O(moisture) → 2Fe2O3.xH2O(rust)
Corrosion of copper:
Cu(s) + H2O(moisture) + CO2(from air) → CuCO3.Cu(OH)2(green)
Corrosion of silver:
Ag(s) + H2S (from air) → Ag2S(black) + H2(g)

Rancidity

It refers to the oxidation of fats and oils in food that is kept for a long time. It gives foul smell and bad taste to food. Rancid food causes stomach infection on consumption.
Prevention:
(i) Use of air-tight containers
(ii) Packaging with nitrogen
(iii) Refrigeration
(iv) Addition of antioxidants or preservatives