Science Reviewer EM Waves PDF

SCIENCE REVIEWER EM WAVES electromagnetic waves - Transverse waves without a medium they can travel through empty space They travel as vibrations in electrical and magnetic fields MICHAEL FARADAY ⁃ Formulated the principle behind electromagnetic induction HENRI HERTZ - Show the experimental evi...

SCIENCE REVIEWER EM WAVES electromagnetic waves - Transverse waves without a medium they can travel through empty space They travel as vibrations in electrical and magnetic fields MICHAEL FARADAY ⁃ Formulated the principle behind electromagnetic induction HENRI HERTZ - Show the experimental evidence of electromagnetic evidence in their link to light HANS CHRISTIAN OERSTED - Showed how a current carrying wire behaves like a magnet JAMES CLERK MAXWELL ⁃ Contributed in developing equations that showed the relationship of electricity and magnetism ANDRE MARIE AMPERE - Demonstrated the magnetic effect based on the direction of current PROPERTIES OF ELECTROMAGNETIC WAVES They move energy as well as momentum from one place to another They travel in a direction perpendicular to particle vibration they are transverse waves They can travel on empty space (vacuum) They can bounce off from a surface (can be reflected) Their direction can change in moving from one medium to another They will be the general wave equation speed equals frequency X wavelength They travel with a speed of 3x10^8 m/s in vacuum The shorter the wavelength or higher the frequency, the higher the energy and thus more dangerous TRANSMISSION AND PROPAGATION OF EM WAVES (non - ionizing radiation) Radio Waves: This is the part of the EM spectrum that emits the longest wavelengths and lowest frequency of radiation waves television, satellites, walkie talkies, radio Microwaves: This is the part of the EM expect that is basically high frequency radio wave which is easily focused into narrow beams bluetooth, wifi, xbox, cooking and radar. Infrared Waves: This is the part of the EM spectrum we are most often exposed to. It is invisible to human , but we feel it as heat Remote controls, room heaters, night vision goggles. Visible Light Waves: This is the part of the EM spectrum that humans can see ( Red, orange, yellow, green - Blue, indigo, violet) and visible light falls in the middle of the spectrum Rainbows Ultraviolet Waves: This is the part of the EM spectrum that is invisible the humans, yet many insects use this Sunburn, A cause of skin cancer, black lights X-ray Waves: This is the part of the EM spectrum that is invisible humans and is known to affect cell division Archeology, medical diagnosis, radiation therapy, laser refinement Gamma Rays: This is the part of the EM spectrum that has the shortest and the highest frequency of radiation waves CT scans Two types of Radiation: Ionizing Non - ionizing Short wavelength > Lowest frequency Short Wavelength > Highest frequency The higher the frequency the higher the energy. REMEMBER Electromagnetic radiation is all around us It travels at the speed of light Electromagnetic radiation can be harmful It plays a crucial role in communication Electromagnetic radiation is used in various technological applications IONIZING VS. NON - IONIZING RADIATION I Short wavelength/ high frequency Has sufficient energy to produce ions in matter at the molecular level Produces enough energy to shake an electron off an atom Breaks chemical bonds Alpha, Gamma, X-rays NI Longer wavelength/lower frequency lower energy  Does not produce enough energy to shake an electron off an atom, nor to break chemical bonds UV rays, Visible microwave, Radio waves Light Light is another time that carries energy. A light ray us a narrow beam of light that travels in a straight line. The material through which a wave travels is called a MEDIUM. When light waves strike an object some light waves might be absorbed by the object, some waves might be reflected from the object, and some waves might pass through the object Material can be opaque, translucent or transparent, depending on how much light passes through the material Light is an electromagnetic wave that can travel in a vacuum as well as through matter Color The light from the sun might look white, but it is a mixture of colors. The Color of an object is the color of all the colors ranging from red to violet Light waves with different wavelengths have different colors Primary Colors Red Blue Green Primary Pigment Colors Yellow Magenta Cyan According to the LAW OF REFLECTION The angle of incidence is equal to the angle of reflection. This is true for any surface, no matter what material it is made of ⁃ A rough surface causes parallel light rays to be reflected in many different directions ⁃ A smooth surface causes parallel light rays to be reflected in a single direction. This type of surface looks like a mirror Plane Mirror - Seems to be same distance behind the mirror as the person is in front of the mirror The angle of incidence equals the angle of reflection Scattering occurs when light rays travelling in one direction are made to travel in many directions Forms a image that is reversed left to right and seems to be behind the mirror Concave Mirror - Has a surface that’s curved outward (like the bowl of a spoon) Reflects all light rays travelling parallel to the optical axis so that they pass through the focal point Convex Mirror - Upright and smaller than the object Causes light rays that are traveling parallel to the optical axis to spread apart after they are reflected Concave and Convex Convex curve outward and make light rays diverge Convex always upright and smaller than the object Concave curve inward and make light rays converge Concave can be either upright or inverted and can vary from larger to smaller than the object Air - The speed of light in empty space is about 300 million m/s. Glass - 197 million m/s Water - 227 million m/s Diamond - 125 million m/s A lens is a transparent object with at least one curved side that causes light to bend A lens that is thicker in the center than at the edges is a convex lens A lens that is thicker at the edges than in the middle is a concave lens Optical Fibers are thin, flexible, transparent fibers. Like a light pipe used commonly in the communication industry Total Internal Reflection Total internal reflection occurs at the boundary between two transparent materials when light is completely reflected Optical fibers use total internal reflection to transmit information over long distances with light waves Microscopes - used to view parts of the universe that cant be seen with the unaided eye Laser Light Light from a laser contains light waves that are in phase, have only one wavelength and travel in the same direction Because laser light does not spread out much as it travels the energy it carries can be applied over a very small area Camera use a convex lens to form an image on light-sensitive film A refracting telescope uses a large objective lens and an eyepiece lens to form an image of a distant object A reflecting telescope uses a large concave mirror that gathers light and an eyepiece lens to form an image of a distant object Alternating Current - A current that constantly changes direction. It is produced by most electrical generators Commutator - Part of a motor that enables the coil to rotate using direct current Direct Current - Always flows in the same direction. It is produced by cells and batteries Generator - Converts mechanical energy into electrical energy Induction - Generating a current wire by moving the wire in a magnetic field, or by moving a magnet inside a coil. Motor - Converts electrical energy to mechanical energy Slip rings - parts of a generator that enable the rotating coil to produce alternating current Power Stations use generators to produce electricity on a large scale. Mechanical energy is provided by rotating turbines that can be powered by: High pressure steam - In coal, oil, gas and nuclear power stations Wind - In wind turbines Falling Water - In hydroelectric power stations If a wire is moved across a magnetic field, a current is produced. This is called ELECTROMAGNETIC INDUCTION. Induction also occurs if a magnet is moved in a coil of wire, or if a coil of wire rotates in a magnetic field The wire and magnetic field move PERPENDICULAR to each other. If they move PARALLEL to each other, no current is induced. Motors powered by mains electricity use ALTERNATING CURRENT (AC). These motors use electromagnets rather than permanent magnets.