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Electromagnetic team

Electromagnetic team. Arnie, Hamlet, Pistek, Super T, Njrcko, (A)Lara and Su-Ana. SEMINARS. Infrared spectroscopy – Balazs Radon – Petra Mobile phones – Tanja Home – made radio – Stefan Animal vision - Robert. Electromagnetic spectrum. RADIO RECIEVER. Štefan Mikuž

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Electromagnetic team

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  1. Electromagnetic team Arnie, Hamlet, Pistek, Super T, Njrcko, (A)Lara and Su-Ana

  2. SEMINARS • Infrared spectroscopy – Balazs • Radon – Petra • Mobile phones – Tanja • Home – made radio – Stefan • Animal vision - Robert

  3. Electromagnetic spectrum

  4. RADIO RECIEVER Štefan Mikuž Visnjan 27.7.2003

  5. Components of simple radio • Antenna • Coil • Variable capacitor • Germanium diode • Capacitor • Headphones • Wire in the ground

  6. My work • First I come to idea to make a simple radio. • We found a site: http://my.integritynet.com.au/purdic/crystal_set.htm • Then I made a coil. • After that I put together a coil, germanium diode and capacitor. • I fixed a variable capacitor and connected headphones. • At last I connected antenna and wire leading in the ground.

  7. How this radio works? Antenna receives a radio waves from the space. Energy of the wave starts to move electrons in antenna. This current from the antenna is charging radio. So we don’t need any other generator. With variable capacitor and a coil we can find frequency of radio station that we want to listen.

  8. The radio signal is modulated, it has to be demodulated. For this we this we need a germanium diode. The last three things are headphones whit which we can hear the radio station, another capacitor and wire leading in the ground, with this two things we have better signal.

  9. Introduction to mobile phones

  10. 832 frequencies are used per carrier • in each cell 56 voice channels available • MTSO - central office that handles all phone connections and controls basestations in region

  11. communication between cells and mobile phones • SID ( System Identification Code) – 5 digit number each mobile phone has for • “talking” with base station through control channel to confirm its home system. • communications between mobile phones and MTSO • registration request – mobile phone sends request to MTSO through base station • to tell in which cell it is.

  12. Duplex voice channel Mobile phone is duplex channel device It has two separate frequencies, one used for talking and another for listening Both parties can talk at same time

  13. How to transmit information • Frequency division multiple access (FDMA) puts each call on different frequency • Time division multiple access (TDMA) each call gets a certain portion of time on a designated frequency • Code division multiple access (CDMA) each call gets unique code which spreads over available frequencies

  14. Electric field of the mobile phone By Balazs & Robert

  15. Isotropic electric field probe (BA01) Frequency range: 500 kHz-3GHz Full scale: 120 V/m Sensitivity: 0.5 V/m

  16. 1 2 3

  17. Electric field on the surface of the mobile phone 12,5 V/m 68,0 V/m 29,5 V/m 15,0 V/m 24,0 V/m 16,0 V/m

  18. SAR ( Specific Apsorbtion Rate ) • SAR is a measure of the maximum energy absorbed by a unit of mass of exposed tissue of a person using a mobile phone. • SAR = σ|Ei|2/2ρ • European exposure limits : 2.0 W/Kg in 10g of tissue (ICNIRP 1998)

  19. Comparison of our measurements with SAR

  20. Ionizing radiation By Petra & Tanja

  21. Alpha particles • Beta particles • X-rays and gammarays • Neutrons

  22. Background radiation Man – made radiation

  23. How it effects on human health? • high levels of exposure are dangerous • cancers,leukemia,genetic mutations, death • lower level of exposure are used for chemotherapy, surgery, puryfing food

  24. ALARA • Geiger-Muller counter

  25. ALARA-experiments

  26. ALARA- cave

  27. Ion measurements by: Petra Korlević

  28. How ions are formed? • radioactive radiation • electromagnetic radiation • water, lightening, heat... How many… • average: positive 250-1500 ions per cm³ negative 200-800 ions per cm³

  29. Why ions? • problems (asthma, ionizing radiation, irritation, tension, exhaustion, headaches, dizziness, depression…)http://www.static-sol.com/library/articles/air%20ion%20effects.htm • measuring the dormitory (place where we work, conditions)

  30. Radon • major background radiation • product of uranium decay • radioactive gas, situated mostly near the ground • 2nd main reason of lung cancer • 40% of the positive ions come from radon

  31. How did we measure? • ionometer- charged cylinder- current- voltage • - and + ions

  32. Where did we measure? • dormitory (24.) • cave (4.)

  33. Graph 1. – day (21.07)

  34. Special conditions...

  35. Special measurements…

  36. Always look on the bright side of life……..

  37. THE END…. … or is it? 

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