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### Newton's First Law of motion

Hi all

What comes to your mind when you think about Newton's first law of motion . Now a days it has become an obvious statement but it was not the case when the law has been formulated. Statement of Newton's first Law of motion is

" Every body continues to be in state of rest or uniform motion untill acted upon by a net external force."

Equilibrium of the bodies is the essence of the forst law of motion.

Why we have used the word net force it is because there might be more then one forces acting on the body and net force on the body is the vector sum of all the forces acting on the body. Newton's first law of motion only gives the qualitative defination of the force that is it tells us that force is only the influence behind the moving objects but it does not tell anything about what is required to keep objects moving when they are set to motion by the application of force. In out daily life we see that bodies set to motion eventualy came to rest for example book placed on a horizontal surface is pushed , it started to move and then come to rest. What does first law of motion has to explain about this effect. What would we have to do to keep the book moving ? Can first law of motion has anything to say about it. Think about it if you find any more point to discuss let me know I'll be happy to discuss

Physics Expert
For complete notes on Newton's Laws of motion visit Newton's Laws of motion

### Electrostatics

You all know physicsgoeasy is my blog and i had already given a good amount of notes on basic electrostatics in this blog so I did not intend to write further on basic electrostatics topics. For detailed basic notes on electristatics you can visit my website physicscstalyst.com and links to my blog postes of electrostatic related material are given below.
Learn Physics for IITJEE , AIEEE , PMT and CBSE Board Examination: Electricity Index: "Electric Charge and Coulumb Law Electric Field Charge Density And Conductor Electricty Test Series -1 Electric Potential Electric Flux and G..."
However I will discuss complicated and higher level electrostatic related topics in this blog.

### Crystals

Many materials like carbon can exist in various forms for example it can exist as diamond in solid form and graphite is also one form of carbon and clearly dimond and graphite have different mechanical, thermal, optical and electrical properties. These properties of different forms of carbon can be understood in terms of carbon atoms in the solid structure.
The atoms having no regular arrangement of atoms in their structure are called amorphous solids and those having regular or orderly arrangement of atoms in their structure are called crystalline solids. Graphite is an amorphous solid and diamind is a crystalline one.
Crystalline solids or crystals have periodic arrangements constructed by infinite repetion of identical structural units in space. In simple crystals structural unit is a single atom but it could be group of atoms or molecules attached to every lattice point. Structure of all crystals is described in terms of lattice.
One of simple type of crystal structures is Sodium chloride is a crystal structure having face centered cubic crystal lattice. Its basis consists of one Na and one Cl atom separated by half the body digonal of a unit cube. Each atom in sodium chloride cryatal has six nearest atoms of opposite kind. Space lattice of diamond is a face centered cubic crystal. The conventional unit cube of a diamond crystal contains 8 atoms and the basis of diamond contains only one atom that is carbon atom. Thus each point of fcc lattice have two identical atoms attached as its primitive basis.
This post is purely an informational one and is beyond your course you intend to study for your board and competetive exams.

### Properties of light

1. Speed of light is greatest in the vacuum and it approximate value is 3 x 108. This value of speed of light is same for all wavelengths.
2. light has got dual nature i.e., sometimes it acts as particles and sometimes a s waves depending on the situation for example Einstein photoelectric effect experiment establishes particle properties of waves and experiments like interference and diffraction of waves establishes wave nature of light.
3. Light waves does not require any medium for its propagation.
4. When light waves travels from one medium to another it's frequency remains unchanged however its wavelength and speed do changes with the change of medium.
5. Frequency of light determines its frequency.
6. Light follows the path along which it takes less time to travel from one place to another i.e., it travels in accordance to Fermat's principle.
7. All bodies which emits light are known as sources of light and light sources can be of any shape or size.
8. When a source of light possess its own it is termed as luminious for example sun and if it does not have its own light but it visible because of reflected light from it then it is known as non luminous source of light for example human body etc..