Heat transfer| Radiation| what us radiation | Newton law of cooling|

 ***ELECTROMAGNETIC SPECTRUM:- The  orderly arrangement of electromagnetic wave in increase or decrease order of wavelength or frequency is called electromagnetic spectrum.

***RADIATION   :--

If the body temperature is more than 0K, the body transfers heat energy in the form of electromagnetic wave, this mode of heat transfer is called radiation.

:--The mode of heat transfer by radiation does not require a medium.

:- Electromagnetic waves can have different wavelength and can travel in vacuum with the same speed of light that is equal to 

 3× 10⁸ ms⁻¹.

:-heat energy is carried by infrared waves with wavelength greater than 750nm.

***Newton Law Of Cooling:--

The rate of loss of heat of the body is directly proportional to the difference of temperature of the body.

Q₁  A pan filled with hot food cool from 90°C to 86 °C in 120 seconds when the room temperature is at 20°C . how long will it lakes to cool from 71°C to 69°C? 

Ans :- 42 seconds