Science Class Project

By: Gabriela Guerra, Omar Ruiz, Ignacio Acosta & Alejandro Acosta Science Project By: Omar Ruiz, Alejandro Acosta, Gabriela Guerra & Ignacio Acosta

Lesson 1: Electromagnetic Radiation

LESSON 1: ELECTROMAGNETIC RADIATION

• Electromagnetic waves are waves that can travel through empty space and matter.

• Radiant energy is energy carried by electromagnetic waves. An electric charge is surrounded by an electric field. If the charge moves up and down, the field also moves up and down.

LESSON 1 CONT.

• A changing electric field produces a magnetic field. The vibration of the charge starts a wave of vibrating electric and magnetic fields that moves outward in all directions.

• When the electric field is the strongest in one direction, the magnetic field is the strongest to that perpendicular direction.

WAVELENGTH AND FREQUENCY• Wavelength and frequency: A Wavelength is the distance

between one point on a wave to the nearest point just like it. Frequency is the number of wavelengths that pass by a point in a certain period of time.

• Wave speed is its frequency multiplied by its wavelength, to determine the wavelength divide the speed of light by frequency of waves.

WAVES CONT.

• Not all electromagnetic waves are visible by the human eye. Some waves such as ultra violet light reach the earth and can damage your skin by having a sun burn.

• These waves have greater frequency than other. Other sources of energy such as a flashlight do not have the energy to damage your skin. Mechanical waves are related to its amplitude. A water wave has lots of amplitude.

THE SUN

• Most of the energy is received from the sun. The sun’s energy is divided into light, with 44%; infrared, with 49%; and ultraviolet, with 7%. One type of energy it gives us is thermal energy. Only a small amount of waves reach Earth.

• Another source of electromagnetic waves is the explosion of stars. Sources of electromagnetic waves on Earth are campfires, and light bulbs.

LESSON 2: THE ELECTROMAGNETIC SPECTRUM

• The electromagnetic spectrum is the entire range of electromagnetic waves with different frequencies and wavelengths.

• There are seven types of electromagnetic waves. One type is a radio wave, this wave has low frequency and low energy. This electromagnetic wave has a wavelength of 30 cm, some radio waves have wavelengths as long as a kilometer or more.

• A microwave is a wave that has low frequency and low energy. These electromagnetic waves have a wavelength between about 1 mm and 30 cm.

LESSON 2 CONT.

• An infrared wave is electromagnetic waves that have a wavelength shorter than a microwave but longer than a light.

• Vibrating matter makes infrared waves. Light is electromagnetic waves that your eyes can see. Red light is has the longest wavelength and the lowest frequency.

• Violet light has the shortest wavelength and the higher frequency.

ULTRA VIOLET

• An ultra violet wave that has a shorter wavelength and higher frequency than light can carry enough energy to cause chemical reactions.

• An x -ray is a high energy wave that has a slightly shorter wavelength and higher frequency than an ultraviolet wave.

• A gamma ray is a high energy electromagnetic wave with a shorter wavelength and higher frequency than all the other electromagnetic waves.

Lesson 3: Using electromagnetic waves

LESSON 3: USING ELECTROMAGNETIC WAVES

• Radio waves: Radio waves are obviously the waves that send out signals for radio shows and television.

• They travel trough air at the speed of electromagnetic waves, and they don´t harm humans.

• Its wavelenght is long enough to go around many objects.

• Broadcasting is the use of electromagnetic waves to send information in all directions.

• This became possible when scientists learned to use radio waves.

CARRIER WAVES

• How do your radio and television receive information to produce sounds or images?

• Well the answer is simple: carrier waves.

• A carrier wave is an electromagnetic wave that a radio or television station uses to carry its sound or image signal.

• First the station modulates, or varies, the carrier waves to match the electrical signal. Then the signal gets converted back into images or sounds when it reaches your radio or television.

• There are also two ways a station might change a carrier wave.

MODULATION

• Amplitude modulation is the change in the amplitude of a carrier wave. Meaning it changes the distance a wave carries from its rest position.

• The other way to change a carrier wave is frequency modulation, which just like the name says, it´s a change in the frequency of a carrier wave. A change in frequency matches a change in sounds or images.

• When a amplitude-modulated wave changes smoothly from high to low that is known as analog.

DIGITAL SIGNALS

• Digital signals change in steps. For a station to send a digital signal they have to change some properties of a carrier wave.

• The station might send the signal as pulses, or a pattern of starting and stopping. It might even have a code of high and low amplitudes.

• Sounds and imagines sent by digital waves are usually clearer than analog signals.

STEP OF BROADCASTING

• The steps of how a radio station broadcasts a signal are the following:

1. A stations transmitter produces an electric signal to match sounds such as music or voices.

2. The station uses the signal to push electric charge up and down an antenna. This vibrating charge in the antenna produces the radio waves.

3. A receiving antenna detects waves with a frequency you choose. The radio waves push electric charge in the antenna, producing an electric current.

4. Finally a loudspeaker uses the electric current to reproduce the original sounds.

• Television transmission is similar, but for this, the waves travel trough cables designed to carry radio waves.

MICROWAVES

• Microwaves are useful for sending and receiving signals, but microwaves can carry more information than radio waves because their wavelength is shorter.

• Microwaves can also easily pass trough some, light rain, snow, and clouds.

• Cell phone companies set up small regions of service called cells.

• Each cell has an antennae where when you make a call you phone send and receives signals to and from that cell tower.

• For a signal to get to the phone of the

person you called it most pass from

cell to cell until it reaches it.

COMMUNICATION

• Communication with satellites is similar to communication with antennae on Earth do.

• Transmitters send microwaves signals to the satellites and this signals can be passed to other satellites or other places on Earth.

• One vary famous use of satellites communication is the Global Positioning System or as we know it GPS.

• GPS is a worldwide navigation system that uses satellite signals to determine a receiver´s location.

• At least 24 satellites continually orbit Earth sending different signals.

INFRARED WAVES

• Vibrating molecules in any matter emit infrared waves.

• The wavelength of this waves depends on the object´s temperature. Hotter objects emit infrared waves with a higher frequency and a shorter wavelength.

• Infrared imaging happens because of thermal cameras that take pictures by detecting infrared waves rather than light waves.

• They convert this waves or different temperatures into colors so that your eyes can interpret the image.

• Scientist launch satellites that detect and photograph infrared waves coming from Earth.

• This images show vegetation, snowfall, fire smoldering, lava flowing from a volcano, etc.

LIGHT & ULTRAVIOLET RAYS

• Even though most of the light on Earth comes from the Sun the one emitted on Earth also has important uses.

• We need electrical lights for businesses, street lights, traffic signals, movie theaters, some forms of communication, etc.

• Ultraviolet rays can affect your skin if you are too exposed to them, but they also help kill germs and also some materials glow when ultraviolet waves strike them.

• Like secret codes on credit cards can be seen with ultraviolet rays and campers can purify water with ultraviolet rays.

ULTRAVIOLET RAYS

• Ultraviolet rays are also used for medical uses like cleaning tools and surfaces by bringing them close to ultraviolet lamps.

• Are also used to control or cure certain skin problems like psoriasis. As the patient is exposed to ultraviolet light several times a week the waves carry enough energy to slow the growth of the diseased skin cells.

• Also dentist use it to harden an adhesive in just seconds. Without the ultraviolet light it would take much longer.

• Also flourescents lightbulbs use ultraviolet waves to produce the light. The chemical absorbs the energy of the ultraviolet waves in the lightbuld and reemits it as light.

X-RAYS

• X-Rays have even more energy than ultraviolet waves. They don’t only pass the skin, but also the muscle. This makes them dangerous and useful for medical imaging and security.

• They are used for security scanning because they can pass trough many materials except metals. Computers create images of what the X-rays are scanning.

X RAYS

• For medical detection the x-rays pass trough different soft parts of your body (can´t pass trough bones). Light parts of the photographic films show where the bone absorbed the x-rays.

• Now days it exist a computed tomography scanner (CT) that is a x-ray machine that around a patient, producing a three dimensional view of the body.

GAMMA RAYS

• Gamma rays have an extremely high energy that can be used to destroy diseased tissue in a patient.

• They can also be used to diagnose medical conditions.

• Gamma rays are formed when an atoms nucleus breaks apart or changes.

GAMMA RAYS

• With PET ( Positron Emission Tomography Scan) a detector monitors the breakdown of a chemical injected into a patient.

• The chemical is attracted to diseased parts of the body. The detector can see the location of the disease by detecting the gamma rays emitted by the chemical.

VIDEOS & DEMOSTRATIONS

• http://www.youtube.com/watch?v=cfXzwh3KadE

CHAPTER SUMMARY LESSON 1

• Electromagnetic waves are waves that can travel through empty space and matter. These waves carry radiant energy.

• Electric charges are surrounded by electric fields so if the electric charge moves so does the electric field. When an electric field moves, it creates a magnetic field that moves in a direction perpendicular to the electric field.

• Wavelength is the distance between one point and the closest point just like it.

• Frequency is the number of wavelengths that pass by a point in a certain amount of time.

CHAPTER SUMMARY LESSON 1 CONT.

Frequency Wave length

Wave speed

CHAPTER SUMMARY LESSON 2

• A microwave has low frequency and low energy. These electromagnetic waves have a wavelength between about 1 mm and 30 cm. Like radio waves, microwaves are used for communication, such as cell phone signals. With shorter wavelengths than radio waves, microwaves are less often scattered by the air.

• Vibrating matter makes infrared waves.

• Light is electromagnetic waves that your eyes can see.

• An ultra violet wave has a shorter wavelength and higher frequency than light and carries enough energy to cause chemical reactions.

• An x -ray is a high energy wave

• A gamma ray is a high energy electromagnetic wave with a shorter wavelength and higher frequency than all the other electromagnetic waves.

CHAPTER SUMMARY LESSON 2

• Lesson 2

CHAPTER SUMMARY LESSON 3

• Radio waves are waves that move at the speed of electromagnetic waves and don’t harm humans

• Carrier waves are the waves that carry information to your TV or radio.

• First the station modulates the carrier wave so that it can be read by your TV. There are two ways a station can do this.

• -Amplitude modulation: change the amplitude of a wave.

CHAPTER SUMMARY LESSON 3 CONT.

• -Amplitude modulation: change the amplitude of a wave.

CHAPTER SUMMARY LESSON 3 CONT.

• Frequency modulation: changes frequency of wave.

CHAPTER SUMMARY LESSON 3 CONT.

• Digital signals: sometimes a station has to change some properties and turn it into a pulse.

• In today’s world, electromagnetic waves are at the heart of everything, the phone you use the light from some light bulbs, some medical procedures and many more things require electromagnetic waves. This is why people are scared of solar flares. Solar flares could disrupt the way electromagnetic waves behave all around the world and this would basically take away most of our technology.