polymer

1. A polymer is a large molecule (macromolecule) composed of repeating structural units. They are connected by covalent chemical bonds. ( structural unit is a building block of a polymer chain)

2. Natural polymer such as natural and cellulose, which is the main constituent of wood and paper

3. Synthetic polymers  such as  synthetic rubber,nylon, PVC, polystyrene

organic compound

Organic compound

1. An organic compound is any member of class of gaseous,liquid or solid chemical compounds whose molecules contain carbon 

2. Example methane ,carbamate

Color and heat absorption

Knowing why darker colors absorb more heat

1.  As darker colour are good absorbers of heat, they are also good absorbers of light.

2. The color of an object depends on the wavelengths of colors reflected from the object.

3. A red apple is red because red wavelengths in visible light are reflected and other wavelengths are absorbed.

4. In fact, if a red apple were to be illuminated by light that had no red wavelengths, the apple appear almost black. 

5. We can see the red colour of apple as our eyes enables to detect the red frequency  in visible light that reflected from the object to our eyes.

6. When a black object is illuminated by white light, all wavelengths are absorbed and none are reflected -- that's why the object appears black.

7. when light is absorbed by a black object, the energy carried by the light doesn't just disappear. Rather, it raises the energy of the object doing the absorbing. 

8. The object, in turn, releases the absorbed energy by emitting longer wavelength, lower energy infrared (heat). 

9.  Light just doesn't disappear when it strikes a black object -- it's transformed into another kind of radiation that is either radiated from or retained within the black object. 

10.This transformation of light into heat is in line to the law of conservation of energy.

11.The darker the object, the better its emission of heat because it is a better absorber of light.

12.Hence,the reason dark colors are dark is that they absorb light instead of reflecting it. Since light is energy, absorbing light makes something hotter. 

Complex Number

1. It is a number consisting of a real part and an imaginary part.

a.Real part – it is a quantity along quantinum,example an integer (5 /-5),rational number (3/4) etc.

 

b. Imaginary part / imaginary number  -It  is any number whose square is a real number less than zero. Imaginary numbers have the form bi where b is a non-zero real number and i is the imaginary unit, the square of an imaginary number is always negative. example, i ² = −1

2. An imaginary number bi can be added to a real number a to form a complex number of the form a+bi, where a and b are called, respectively, the "real part" and the "imaginary part" of the complex number

3. Example, −3.5 + 2i is a complex number.

4. The real number a of the complex number z = a + bi is called the real part of z and the real number b is the imaginary part.

5. They are denoted Re(z) and Im(z) respectively.

Credit :wikipedia/complex number,real and imaginary number

Fraunhofer lines

    1. The founder of fraunhofer lines was a german physicist named Joseph Von fraunhofer.

2. Fraunhofer lines are a set of spectral lines that appear as “dark” in the optical spectrum of sun.