Properties and uses of electromagnetic waves

 Properties and Uses of    Electromagnetic wave

Properties of EM wave:

1. It has transverse nature
2. It does not deflected in electric and magnetic fields
3. All the EM waves travel with the same speed in  vacuum

            with the speed of light (c= 3x 10⁸ m/s)

4. No material medium required for its propagation
5. They get refracted ,diffracted and polarised

6. They have oscillating electric and magnetic fields which are mutually perpendicular to each other and also perpendicular to the direction of propagation of wave
7. Electromagnetic waves can transfer energy as well as momentum to objects   placed on their paths.
8. The arrangement of electromagnetic waves according to their wavelength is called as Electromagnetic spectrum

For video lecture: https://youtu.be/HtTlPSGb_gg

Electromagnetic spectrum :

The arrangement of electromagnetic waves according to their wavelength is called as Electromagnetic spectrum  

code : GXUVIMR

         γ rays   x rays  Ultra violet rays   visible light,  Infrared rays ,  Microwaves ,Radio waves

G for γ rays, X for x rays , U for Ultra violet rays ,v for visible light, I for infrared rays , M for Microwaves ,R for Radio waves

   (i) γ- rays:

The main sources are natural and artificial radioactive substances

USES:

1. γ –rays are used in medicine to destroy cancer cells
2.  γ- rays are used in nuclear reaction because of their high penetrating power
3.  γ-rays effect the photographic plat                                                                                                                                                                                       (ii) X-rays:

              X rays produced in X-ray tubes when high energy electron bombard on metal plate

X rays damage or destroy living tissue and organism, Care must be taken avoid unnecessary or over exposure

1. These are mainly used in detecting the fracture of bones, Tuberculosis of lungs, Presence of stones in gall bladder and kidney, hidden bullet or needle.

2. X-rays are used to study the crystal structure.

3. X-rays are used in engineering to detect flaws in bridges.

4. X-rays are used to cure cancer.

(iii) Ultra violet rays:

These rays produced by special lamps and very hot bodies. Sun is the important source of UV rays.

Uses:

1. Due to it’s short wave length these are used as LASIK(Laser Assisted In Situ Keratomileusis) eye surgery.

(iv) Visible light:

These are part of electromagnetic spectrum detected by human eye.

These are used to see objects (vision effect ) provides information about the world

(V) Infrared rays :

 All hot bodies are sources of IR radiations

Uses:

1. IR rays are used for taking photographs during the condition of fog , smoke and so on
2. IR rays are used to treat muscular strains i.e. physiotherapy
3.  IR rays widely used in remote switches of household electronic systems i.e. television, AC
4.  IR rays are use for weather forecasting

  

(V) Infrared rays :

 All hot bodies are sources of IR radiations

Uses:

1. IR rays are used for taking photographs during the condition of fog , smoke and so on
2. IR rays are used to treat muscular strains i.e. physiotherapy
3.  IR rays widely used in remote switches of household electronic systems i.e. television, AC
4.  IR rays are use for weather forecasting
5. IR detectors are used in earth satellite both military purpose and to observe the growth of crops
6. IR rays are used to provide electrical energy to satellite by using solar cell

7.                7. IR rays are used in solar water heaters and solar cookers

8.               8. IR rays from the sun keep the earth warm &hence help to

 sustain life on the earth through the greenhouse effect

vi) Micro waves :

These are produced by special vacuum tubes called as klystrons ,magnetrons and Gunn diodes

These are shorter wavelength radio waves

Uses:

1. Microwaves are used in radar system for aircraft navigation because of their short wavelength
2.  Based on microwaves speed guns are designed which are used to find the speed of fats moving balls ,automobiles

 Microwaves are used in microwave ovens used to heat the food items (Domestic application

Principle of microwave oven:

Frequency of microwave is equal to the resonating frequency of water molecules in food items so that energy of EM wave transferred effectively to the kinetic energy of molecules. This rises the temperature of food containing water

(vii) Radio waves:

Radio waves are produced by the accelerated motion of charges  in conducting wires .

Uses:

These are used in radio ,TV and cell phone communication

Radio brand frequency range : 88MHz to 108MHz

TV brand frequency range  : 54MHz to 890MHz

Cellular Brand frequency range: 300MHz to 3000MHz

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