1. 9EE605A.11 Name Designation Branch Institute Year/Semester Subject Subject Code Topic Duration Sub Topic Teaching Aids : P. Balanarsimlu : Lecturer : Electrical Engineering : Govt. Polytechnic Nizamabad : VI Semester : Electrical Utilisation and Traction : EE605A : Electric Lighting : 50 Min : Nature of Light and its Propagation : PPT, Diagrams, Animation Department of Technical Education Andhra Pradesh Designation Revised By : K. Chandra Sekhar, L/ EEE, GPT, HYD

2. 9EE605A.12 Objectives On completion of this class you would be able to know The Principles, Nature and its Propagation of Lighting

3. 9EE605A.13 Known To Unknown What is light ? Importance of Light Electrical Light

4. 9EE605A.14 Introduction Electrical power plays an important role in our day to day life and it became part of our life Electrical energy is used in industries, agriculture, transportation, household etc. Utilization of Electrical power became back bone of industrial World for Electric lighting, heating, welding, drives, controls and traction

5. 9EE605A.15 Light Light is an electromagnetic radiation The natural sources of light are the sun and the stars Sun emits both heat and light energy at a very tremendous rate

6. 9EE605A.16 The natural source of light is the sun and stars. Fig.1

7. 9EE605A.17 Fig.2 The natural source of light are the sun and stars.

8. 9EE605A.18 Work which can be done in day time, can also be done equally by means of artificial lighting during night times, which is possible with the help of electricity Electrical Lighting Fig.3

9. 9EE605A.19 The need of understanding illumination engineering is to make the visual environment by reducing strain on the eyes and nervous system Fig.4 Electrical Lighting

10. 9EE605A.110 In the sphere of industrialization, good illumination ensures increased production and reduced fatigue on workers More lighting causes discomfort and less lighting causes strain on eyes So it is necessary to design the lighting scheme in such a way that illumination is proper for proper places Electrical Lighting

11. 9EE605A.111 It is necessary to design the lighting scheme in such a way that illumination is proper for proper places. Fig.5aFig.5b Fig.5cFig.5d

12. 9EE605A.112 Nature of Light and its Propagation Light is a form of radiant energy, its nature depends upon the temperature of the hot body A hot body of about 500 0 C to 800 0 C becomes a red hot and about 2500 0 Cto 3000 0 C becomes white hot In both the cases a part of radiation is in the form of light

13. 9EE605A.113 A part of radiation is in the form of light Fig.6 Nature of Light and its Propagation

14. 9EE605A.114 Nature of Light and its Propagation It is understood that light is a form of energy, which can be radiated like heat and is converted from heat only Fig.7

15. 9EE605A.115 Nature of Light and its Propagation Light radiations can propagate like electro-magnetic waves through a medium in the form of transverse waves Fig. 8

16. 9EE605A.116 Nature of Light and its Propagation The propagation velocity of the radiant energy in a medium is 3 X 10 8 m/sec Different light waves have different frequencies, but the velocity is same

17. 9EE605A.117 Nature of Light and its Propagation The different frequencies of light waves produce different Colour sensation on human eye Fig.9

18. 9EE605A.118 Nature of Light and its Propagation The band width of visible frequencies is 4.3X10 14 Hz to 7.5X10 14 Hz

19. 9EE605A.119 3X10 4 3X10 6 3X10 8 3X10 10 3X10 12 3X10 14 3X10 16 3X10 18 3X10 20 3X10 22 10 4 10 2 1 10 -2 10 -4 10 -6 10 -8 10 -10 10 -12 10 -14 FREQUENCY in Hz WAVE LENGTH in meters Radar, TV and Radio Infrared Ultra violet Gamma, X rays Cosmic rays VISIBLE LIGHT Electromagnetic Spectrum NATURE OF THE WAVES 4.3 X 10 14 Hz 7.5 X 10 14 Hz Fig.10

20. 9EE605A.120 Nature of Light and its Propagation The range of wave lengths can perceive sensation of Colour on human eye is 4000 A 0 to 7500A 0 (0.004mm to 0.0075mm) Fig.11

21. 9EE605A.121 Nature Of Light and Its Propagation Short wave length --- Violet and Blue Medium wavelength --- Green Yellow and Orange Long Wave length --- Red The sensitivity percentage of eye varies with respect to wave length Fig.12

22. 9EE605A.122 Summary So far we have discussed about Natural Source of Light Nature of Light Propagation of Light Frequency and Wave Length of Light Electromagnetic spectrum Frequency band of Visible Light

23. 9EE605A.123 1. The Natural Source of Light is A) SunB) Candle C) Kerosene lampD) Gas light Quiz

24. 9EE605A.124 2. Which of the following frequency belongs to light? A) 10 8 HzB) 10 12 Hz C) 10 14 HzD) 10 6 Hz Quiz

25. 9EE605A.125 3. The Velocity of Light is D) 3X10 8 m/sec B) 3X10 12 m/sec C) 3X10 4 m/sec A) 3X10 6 m/sec Quiz

26. 9EE605A.126 4. The range of wavelength of visible light is A) 400A 0 to 750A 0 C) 400A 0 to 7500A 0 B) 4000A 0 to 7500A 0 D) 40A 0 to 75A 0 Quiz

27. 9EE605A.127 1)What is light ? 2)Explain the nature of light and its propagation 3)Draw the electromagnetic spectrum and show the visible light band 4)Explain about Colour sensitivity on human eye Frequently Asked Questions

28. 9EE605A.128 THANK YOU