Electromagnetic waves

definition, speed, production, properties of electromagnetic waves and electromagnetic spectrum. waves in EM spectrum and their application in daily life.

1. ELECTROMAGNETIC WAVES Presented to: Dr. Hazrat Bilal Malakandi, PT Group 1A Member (3 rd semester DPT, Medical Physics) Rabia Naeem Huma Inayat Sidrah Shinwari Najla Amar Iqra Ayub

2. Electromagnetic Waves If you have ever tuned in to listen to a radio ,a spoken headphone , turned on a light ,hand on X ray taken, felt the warmth of the sun on your skin. You have experienced ELECTROMAGNETIC WAVE.

3. Definition “Electromagnetic waves are waves which can travel through the vacuum of outer space . Electromagnetic waves are formed when an electric field couples with a magnetic field. The magnetic and electric fields of an electromagnetic waves are perpendicular to each other and to the direction of waves.”

4. How do moving charges create magnetic fields? Any moving electric charge is surrounded by an electric field and a magnetic field.

5. Production of Electromagnetic Waves When an electric charge vibrates, the electric field around it changes creating a changing magnetic field.

6. The magnetic and electric fields create each other again and again .

7. An EM wave travels in all directions. The figure only shows a wave traveling in one direction.

8. The electric and magnetic fields vibrate at right angles to the direction the wave travels so it is a transverse wave

9. What is the speed of EM waves? All EM waves travel 300,000 km/sec in space. (speed of light-nature’s limit!) EM waves usually travel slowest in solids and fastest in gases.

10. Properties of electromagnetic wave All are electromagnetic waves are transverse They do not required any medium to travel though . They travel at speed of 3 multiple by 10 -8 in vacuum. They can all be reflected and refracted. They can all be emitted and absorb by matter.

11. Graphically Representation

12. Electro Spectrum “Frequencies is called the electromagnetic spectrum.” Different parts interacts with matter in different way As wavelength decreases, frequency increases… The ones humans can see are called visible light, a small part of the whole spectrum .

13. Chart of wave length and frequency

14. Electromagnetic spectrum Includes following types of waves : Radio waves Microwaves Infrared waves Visible light Ultraviolet X rays Gamma rays

15. Region Frequency Wavelength Energy Radio waves < 10 9 > 0.3 < 7x 10 -7 Microwaves 10 9  - 3x10 11 0.001 - 0.3 7x10 -7  - 2x10 -4 Infrared 3x10 11  - 3.9x10 14 7.6x10 -7  - 0.001 2x10 -4  - 0.3 Visible 3.9x10 14  - 7.9x10 14 3.8x10 -7  - 7.6x10 -7 0.3 - 0.5 Ultraviolet 7.9x10 14  - 3.4x10 16 8x10 -9  - 3.8x10 -7 0.5 - 20 X-rays 3.4x10 16  - 5x10 19 6x10- 12   - 8x10 -9 20 - 3x10  4 Gamma rays > 5x10 19 < 6x10 -12 > 3x10 4

16. Radio waves Radio waves have the longest wavelengths of all the electromagnetic waves. Low frequency. Radio waves are often used to transmit data and have been used for all sorts of applications including radio, satellites, radar, and computer networks .

17. Radio waves are used in medicine Is used to produce images of soft tissues, fluid, fat and bone. Example : MRI and RFA. DIAGNOSE MANY PROBLEMS . Example : helps identify tumors. Radiofrequency Ablation (RFA) uses heat to destroy cancer cells.

18. Microwaves Microwaves are radio waves with wavelengths less than 30 cm and higher frequency & shorter wavelength Cell phones and satellites use microwaves between 1 cm & 20 cm for communication

19. Microwaves are useful in communication because they can penetrate clouds, smoke, and light rain. Microwave also in radar that helps to predict the weather.

20. Microwave waves are used in medicine Hyperthermia therapy is a type of medical treatment. Microwave ablation: used in treatment of liver tumor Microwave diathermy : used in pain management Transurethral microwave : thermotherapy used in treatment of lower urinary tract syndrome

21.   Infrared waves : Infrared waves are sometimes classified as "near" infrared or "far" infrared Between microwaves and visible light are infrared waves. Can be detected by heat and used in heat lamp. Higher energy then microwave and lower the visible light. Used daily in remote controls, to read CD-ROMs

22. Precautions Strong infrared radiation in certain industry high-heat settings may be hazard to the eyes, resulting in damage or blindness to the user. Since the radiation is invisible, special IR-proof goggles must be worn in such places

23. Modalities use Infrared lamps Digital infrared camera

24. Infrared Imaging in Medicine Oncology Vascular disorders Respiratory disorders Skeletal neuromuscular diseases Surgery Tissue viability

25. Visible light This is the range of wavelengths from 390 to 700 nm which corresponds to the frequencies 430-790 THz. The portion of the electromagnetic spectrum that human eyes can detect.

26. You see different wavelengths as colors . Blue has shortest Red is the longest Light looks white if all colors are present

27. Visible light use in medicines Visible light is also used in Scanning laser ophthalmoscope. In Endoscopy/ Keyhole Surgery

28. Ultraviolet Waves Ultraviolet waves have the next shortest wavelength after visible light. EM waves with wavelengths from about 400 billionths to 10 billionths of a meter. Used in tanning beds and sterilizing equipments.

29. Ultraviolet Waves use in medicines Have enough energy to enter skin cells Longer wavelengths – UVA Shorter wavelengths – UVB rays Both can cause skin cancer

30. Ultraviolet light is used in treatment of Psoriasis and Vitiligo Pregnancy Abnormalities in the heart and blood vessels Organs in the pelvis and abdomen Symptoms of pain, swelling and infection

31. Can UV radiation be useful Helps body make vitamin D for healthy bones and teeth Used to sterilize medical supplies & equip Detectives use fluorescent powder (absorbs UV & glows) to find fingerprints

32. X Rays High wave energy Used in : Medicines Industry Transportation To much exposure can damage the living tissue or even cause cancer

33. X rays use in medicines X-rays play an important role in dentistry and orthopedic investigation. They can penetrate soft tissue like skin and muscle. Are used to take X-ray pictures of bones in medicine.

34. Gamma rays Gamma rays the highest energy electromagnetic waves The actually come from radioactive elements or stars Inspection tools in industry

35. Gamma rays use in medicines Positron Emission Tomography (PET) is a nuclear medical imaging tool which used gamma rays. Example : Neurological diseases such as Alzheimer’s and Multiple Sclerosis Effectiveness of treatments

36. Heart conditions Gamma Knife uses beams of highly focused gamma rays to treat tumors or other abnormalities in the brain. Gamma rays can check how far a cancer has spread and how well treatment is working.

37. What question do you have?