Electromagnetic Waves

1. Radiowaves

1.1. Longest wavelength

1.2. Smallest energy electromagnetic wave

1.3. Uses : Standard AM FM radio can cover 53-171 kHz

1.4. Used for exploration of of space

1.5. Used in Walkie talkies used by policemen and firemen.

2. Microwaves

2.1. Wavelength of radiation is 3cm to 10cm

2.2. Used for television satellites and microwave regions

2.3. Radar devices emits and receives microwave signals

3. Infra-red Waves

3.1. 1.00mm to 8x10^-7

3.2. Used in IR lasers and TV remote controls

3.3. Erroneously think of IR as heat waves

4. Visible light

4.1. Occupies a small part of electromagnetic spectrum

4.2. low energy red at 7000 A

5. Introduction

5.1. Not Mechanical Waves

5.2. Carried by oscillating electrical and magnetic fields

5.3. Grouped into radio waves, infra - red, visible light and Gamma rays

5.4. Travels with the speed of 3x10^8 ms-1

5.5. Electromagnetic waves artificial grouping and no boundary

6. Ultraviolet

6.1. Wavelength of UV is 4000 to 10 A

6.2. Produce vitamin D in human body

6.3. Used in UV sterilizers to kill microorganisms in water

7. X- Ray

7.1. ability to pass through materials that absorb visible light

7.2. Used in medicine to see inside body without invasive surgery

8. Gamma Rays

8.1. Wavelength are short 10-11 to 10-13

8.2. Caused by radioactive decay

8.3. Nuclear reactions result in emission of gamma rays