• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.