1. Radiant energy اشعاعا الطاقة  Radiant energy is the energy in the form شكل of waves or rays in the ether. الأثير (Radiant energy is one of the mechanisms آليات by which energy can enter أدخل or leave إجازة an open system.)  Waves are set-up in the ether الأثير by movement of electrons حركة الالكترونات & are known as Electromagnetic waves. موجات كهرومغناطيسية  Sunlight ضوء الشمس Is A Form Of Radiant Energy

2.  Electromagnetic radiation (often abbreviated E-M radiation or EMR) is a phenomenon that takes the form of self-propagating نشر الذاتي waves in a vacuum فراغ or in matter.  Electromagnetic Radiation: Electromagnetic waves are produced by the motion of electrically charged particles. حركة الجسيمات المشحونة كهربائيا Because they radiate from the electrically charged particles & they travel through empty space as well as through air and other substances.

3.  It consists of electric الكهربائية and magnetic المغناطيسي field components which oscillate in phase التأرجح في المرحلة perpendicular عمودي to each other and perpendicular to the direction of energy propagation. نشر الطاقة  If currents in an AC circuit change rapidly, some energy is lost in the form of EM waves  EM waves are radiated by any circuit carrying alternating current التيار المتردد

5. 1.Electromagnetic waves are transverse waves الموجات المستعرضة 2.Electromagnetic waves travel السفر at the speed of light سرعة الضوء 3.Electromagnetic waves can travel through a vacuum فراغ or a material substance. مادة مادة 4.Electromagnetic waves carry حمل energy الطاقة as they travel through space, and this energy can be transferred نقل to objects الكائنات placed in their path.

6. 5. Energy carried by EM waves is shared equally مناصفة by the electric and magnetic fields 6. They all have different مختلفة wavelength الطول الموجي and different frequencies. الترددات Long wavelength الطول الموجي الطويل  lowest frequency أدنى تردد Short wavelength الطول الموجي القصير  highest frequency أعلى تردد The higher the frequency the higher the energy.

9.  The crest قمة of a wave is the point on the medium which exhibits the maximum amount of positive الإيجابية or upwards displacement from the rest position.  The trough حوض of a wave is the point on the medium which exhibits the maximum amount of negative السلبية or downwards displacement from the rest position. وضعية الراحة

10.  The amplitude سعة of a wave refers to the distance from rest to crest المسافة من بقية لقمة or the amount of displacement from origin to crest. Similarly, the amplitude can be measured from the rest position to the trough position.  The wavelength الطول الموجي can be measured as the distance from crest to crest المسافة من قمة إلى قمة or from trough to trough. A wave is a repeating pattern.

11.  Wavelength is indirectly proportional النسبي بشكل غير مباشر to the frequency.  The shorter the wavelength the higher the frequency and visa versa longer the wavelength the smaller the frequency.  The unit وحدة for measuring wave length is Angstrong which is one ten millionth of a millimeter.  Velocity سرعة = Frequency x Wavelength  Velocity is constant ثابت for all electromagnetic waves, so the frequency varies inversely proportional with the wavelength.

12.  Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency وضعت في ترتيب زيادة تواتر

14.  The electromagnetic spectrum is the entire of electromagnetic waves arranged range according to their frequencies or wavelengths.  Electromagnetic waves all have different properties. الموجات الكهرومغناطيسية وجميع خصائص مختلفة But they all travel the same speed – what we call “The speed of light”

16.  A. Have the longest wavelengths and lowest frequencies of all the electromagnetic waves.  B. A radio picks up radio waves through an antenna and converts it to sound waves.  C. Each radio station in an area broadcasts at a different frequency. # on radio dial tells frequency.  D. MRI (MAGNETIC RESONACE IMAGING) Uses Short wave radio waves with a magnet to create an image

17.  Radio waves are longer than 1 millimeter  longest waves & lowest energy  Found everywhere. Background radiation of the universe, interstellar clouds  Uses: Radio stations use radio wavelengths to send signals that our radios then translate into sound. Radio Stations transmit EM radiation… not sound.

18.  Microwaves—have the shortest wavelengths and the highest frequency of the radio waves. Used in microwave ovens. ○ Waves transfer energy to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food. Used by cell phones and pagers. RADAR (Radio Detection and Ranging) ○ Used to find the speed of an object by sending out radio waves and measuring the time it takes them to return.

19.  Infrared= below red  Shorter wavelength and higher frequency than microwaves.  You can feel the longest ones as warmth on your skin  Heat lamps give off infrared waves.  Warm objects give off more heat energy than cool objects.  Thermo gram—a picture that shows regions of different temperatures in the body. Temperatures are calculated by the amount of infrared radiation given off. Therefore people give off infrared rays.

20. Infrared wavelengths 710 nm to 1 millimeter (width of a pinpoint to the size of small plant seeds) Infrared light maps the “dust” between stars Some infrared rays penetrate our atmosphere from space

21. EM Radiation: Uses: Remote controls (TV/VCR), radiant heaters, grills, optical fibre communication, night vision. Dangers: Skin burns

22.  Shorter wavelength and higher frequency than infrared rays.  Electromagnetic waves we can see.  Longest wavelength= red light  Shortest wavelength= violet (purple) light  When light enters a new medium it bends (refracts). Each wavelength bends a different amount allowing white light to separate into it’s various colors ROYGBIV.

23.  Visible Light:400 to 700 nm  (size of a molecule to a protozoan)  The sun emits most of its radiation in the visible range, which our eyes perceive as the colors of the rainbow.

25.  Shorter wavelength and higher frequency than visible light  Carry more energy than visible light  Used to kill bacteria. (Sterilization of equipment)  Causes your skin to produce vitamin D (good for teeth and bones)  Used to treat jaundice ( in some new born babies.  Too much can cause skin cancer.  Use sun block to protect against (UV rays)

26. Ultraviolet radiation: 10 – 310 nm (size of a virus). Bees see in ultraviolet. The Sun’s heat is ultraviolet light. Uses: Sun beds, fluorescent lamps and security marking. Dangers: High doses can kill cells. Lower doses can cause cells to become cancerous.

27.  Shorter wavelength and higher frequency than UV-rays  Carry a great amount of energy  Can penetrate most matter.  Bones and teeth absorb x-rays. (The light part of an x-ray image indicates a place where the x-ray was absorbed)  Too much exposure can cause cancer (lead vest at dentist protects organs from unnecessary exposure)  Used by engineers to check for tiny cracks in structures. The rays pass through the cracks and the cracks appear dark on film.

28. X-Rays: 0.01 – 10 nm (size of an atom) Uses: Shadow pictures of luggage and inside the human body. Dangers: High doses can kill cells. Lower doses can cause cells to become cancerous.

29.  Shorter wavelength and higher frequency than X-rays  Carry the greatest amount of energy and penetrate the most.  Used in radiation treatment to kill cancer cells.  Can be very harmful if not used correctly.

30. Gamma rays: 0.01 nm or lower Shortest wavelengths and highest frequency (most energetic) (about the size of an atomic nucleus) Our atmosphere prevents their entry. Gamma rays can result from nuclear reactions taking place in objects such as pulsars, quasars, and black holes.

31.  Uses: Kills harmful bacteria in food, sterilising surgical equipment, killing cancer cells.  Dangers: High doses can kill cells. Lower doses can cause cells to become cancerous.

32.  Reflection - انعكاس  Refraction - الانكسار  Absorption - امتصاص  Inverse square law - مربع القانون معكوس

33.  When a ray strikes a new medium which will not transmit it causes the ray to turned back. عندما راي الضربات الوسيلة الجديدة التي لن إحالته إلى أسباب تحول راي الظهر.  Two features: - the incident radiation, the reflected radiation, and a vertical to the surface from which the angles of the incidence and reflection are measured all lie in the same plane - the angle of incidence and the angle of reflection are approximately equal.

34. LAW OF REFLECTION  The incident ray, the reflected ray, and the normal to the surface all lie in the same plane, and the angle of reflection θ r equals the angle of incidence θ i : الشعاع  الساقط، وتنعكس أشعة، وطبيعي على سطح كل تكمن في الطائرة نفسها، وزاوية انعكاس θr تساوي زاوية السقوط θi

38. Light reflects off rough surface in many directions. Law of reflection – The angle of incidence is equal to the angle of reflection في زاوية السقوط تساوي زاوية الانعكاس

39.  I.R.R. (Infra red radiation)  U.V.R. (Ultra violet radiation) These both lamps use PARABOLIC REFLECTOR

41.  When a beam of light passes from one medium to other the rays are BENT. عندما يمر شعاع ضوء واحد من المتوس ط لأشعة أخرى يعكفون.  This causes the rays to be deflected from its original course by an amount depending on the medium involved & the angle of incidence.

43. REFRACTION

45.  When rays strike the surface of a new medium some may be ABSORBED by the new medium. عندما تكون الأشعة قد ضرب سطح الوسيلة الجديدة بعض تمتصه هذه الوسيلة الجديدة.  The proportion of the rays absorbed depends on the nature of the medium, wavelength of the rays & the angle of incidence.

46.  Different materials absorb different groups of rays, allowing others to pass through.  Window Glass:- It allows visible light & I.R.R to pass while absorbing U.V.R. rays.  X-rays:- These are passed through body tissues but are absorbed by bone.

47.  When the angle of incidence is 90˚ then NO RAYS will be absorbed as they will be travelling parallel to the surface.  If the angle of incidence is 0˚ then the rays are striking the surface so as to make a right angle with it & the maximum rays will be absorbed.

48.  When applying I.R.R & U.V.R. to the patient greater efforts should be made to ensure that the maximum number of rays strike the surface perpendicularly. وعند تطبيق I.R.R U.V.R. وينبغي أن تكون الج هود المبذولة لضمان قدر أكبر من المريض أن الحد الأقصى لعدد أشعةضربة السطح بشكل عمودي.  The angle of incidence is ZERO DEGREES for most effective treatment.

49.  All radiations is subject to the inverse square law.  The relationship between the distance from the source & intensity of radiation is expressed in the inverse square law which states that “ The intensity of the radiation from a point source is inversely proportional to the square of the distance from the source

50.  I = 1/d  I = Intensity of radiation  D = Distance travelled by the radiation.  This has greater practical importance.