Waves

1. Sound Waves and By : Roxanne Leak

2. Microwaves • Microwaves are very short waves of electromagnetic energy that travels at the speed of light. • Microwaves used in microwave ovens are in the same family of frequencies as the signal used in radio and television broadcasting. • Microwaves do not carry enough energy to cause and electric charge. • Microwaves are a form of electromagnetic radiation that is very similar to sunlight and radio waves. • Microwave ovens use various combinations of electrical circuits and mechanical devices to produce and control an output of microwave energy for heating and cooking. • Microwaves cannot pass through metal, so metal containers are unsuitable for cooking or heating. • All microwave energy remains inside the cooking cavity.

3. Microwaves(continued) • The clock on the microwave has an electromagnet that switches on and off rapidly. • In 1947, the first commercial microwave oven hit the market. • Microwaves cook food rapidly and efficiently because, unlike conventional ovens, they heat only the food and not the air or the oven walls. • However, microwaves cannot penetrate deeply into foods sometimes making it difficult to cook thicker food. • These ovens can pass through many types of glass, paper, ceramics, and plastics, but they cannot pass through metal. • The first microwave ovens cost between $2,000 and $3,000. • Microwave your kitchen sponges and plastic scrubbers to sterilize them rapidly and effectively.They carry bacteria and viruses.

4. Precautions For using a Microwave • 1) Stay at least an arms length away from an operating oven. • 2) Never stand directly in front of a microwave oven. • 3) Do not operate an oven when it is empty. • 4) Do not operate an oven if the door will not close properly or it in any way damaged. • 5) Never tamper with the safety interlock switches of the fuse. • 6) Never try to repair an oven yourself. • 7) Never put metal in the microwave. • 8) Use common sense when putting unknowns in the microwave. • 9) If you wear a pacemaker, you should not be near a microwave.

5. Some Facts About Hearing & Sound You Should Know About • 1) Once your hearing is damaged, there is no recovery. • 2) Once you have hearing loss, it will probably get worse with age. • 3) You may not recognize that you are experiencing hearing loss, since it is likely to begin in the high frequencies. • 4) If you seem to be “getting use” to loud music, this may be a sign that hearing damage has already began. • 5) If you hear ringing, roaring or clicking sounds when no outside sounds are present, this may be a sign of hearing loss. • 6) If others seem to mumble, or if you hear them speaking and cannot understand the words you maybe experiencing loss. • 7) Certain drugs, such as quinine and some antibiotics, are toxic to hair cells at high enough doses and can produce permanent hearing damage.

6. Hear Comes The Noise • Sound level is measured in decibels. • Living things use sound to obtain information about the surroundings, and to communicate with others by means of speech and music. • Reflection of sound waves off surfaces can lead to one or two phenomenon- an echo or a reverberation. • Sound is produced by the compression and rare-faction of matter. • Sound waves move through air because a vibrating source produces regular variations in air pressure. • Sound is produced when air is disturbed in some way, for example by vibrating objects. • Reflected sound waves are called echoes. • The longer a person is exposed to loud sounds the greater the effect. A person can recover from a short-term exposure in a period of hours, but the effects of long-term exposure to last for days or weeks. • Hearing is one of the five senses by which sound waves are perceived. • Sound is a longitudinal wave because the motion of the air molecules is parallel to the direction of the motion of the wave.

7. Hear Comes Some Words • Noise is a complex sound, a mixture of many different frequencies or notes not harmonically related and is one of your major senses. • The characteristics of sound include, pitch and loudness. • Pitch is essentially the frequency of the wave. • Loudness depends on the amplitude of the pressure variation wave. • You can also determine direction and distance from what you hear. • Sounds provide information about the environment around you. • Sound has the standard characteristics of any waveform. • Also note that light and radio waves are electromagnetic waves.

8. How does sound connect to water ? • Sound is used for studies of ocean currents and layers, and for mapping out the bottom of the sea. • Military necessity in World War I led to the first use of wound for underwater detection of vessels.

9. Some Questions To Answer • How can I listen to music on my I-pod without going deaf ? • The bigger the earphones the better. The smaller the earphones the worse. Keep the volume low. • How can I use the microwave safely ? • Just follow the tips I gave you and you will be fine.

10. The End