Air and Water?

Air and water are two materials with which everyone is familiar. We live at the bottom of an ocean of air, called the atmosphere. Air surrounds our bodies every minute of our lives, expect when where swimming and bathing. Air may be found almost open hallow in all materials on the surface of the earth. There is air also in many of the hallows and opening of the human body-for example,  our ears, mouth, nose and lungs. All animals breath air, and if deprived of it, they die.

     The waters of seas, lakes, rivers, and streams, cover three-quarters of the earth's surface. Water is necessary for life. The cells of which living things are made are largely water. Water, given enough time, will dissolve almost any substance. this is important, because the materials that nourish living things are dissolved in water. This water makes up the main part of the blood of animals and the sap of plants, the two fluids that carry nourishing materials to cells of living things.

     We shall perform experiments concerning both air and water, because, as we shall see, these two materials are closely connected in many ways.

How Can You Change the Color of a Leaf?

You will use:

     Drinking glass
     Celery stalk
     Red Ink
     Water

Do this:

1. Add red ink to the half-glass of water.

2.Place a celery stalk in the glass. Leave in there for several hours.

3.Cut the stem should red.

4.Cut the stem crosswise in several places to see the tubes that carried the water to the leaves.

Why it works:

     A the colored water was the inside of the tiny tubes in the celery, they draw the water up higher that the level of water in the glass. this is called "capillary action".

Everybody Talks About The Weather

Important Words:

     Barometer - An instrument used to measure the pressure of the atmosphere.
     Thermometer - An instrument used to measure temperature.
     Meteorology - Science dealing with the study of atmosphere and weather.
     Humidity -  Amount of water vapor in the air.
     Radiosonde - A radio device carried aloft by balloon, which relays atmosphere pressure, temperature,    and humidity.

     The weather affects all of us in one way or another, directly or indirectly. A dry spell or a freeze may lessen the yield or fruit, and perhaps destroy some crops entirely, thereby causing shortage of food in some areas; and a short supply means either paying higher prices or doing without. A change of weather can bring about a change in plans, ranging from a battle to a picnic or parade.

      The first thing may people do is in the morning is to look out the window " to see what the weather is." If they have an outside thermometer, they look at that to see what the temperature may be. Or they may consult a barometer. Or they may turn on the radio to get weather forecast. Then based on this information, they will decide what kind of clothes to wear.

     Knowing what the weather will be is important to the farmer, the fisherman, the captain of ship, the pilot of airplane, and people in other occupations. Specially trained people provide this information. These weather people are called meteorologists.  They study the winds, clouds,storms, and other natural happening in the atmosphere.  From what they find out, they try to predict the weather for airlines, electric companies, transportation companies, radio and TV stations, and the Weather Bureau. They assemble weather reports from all over the world, study radar pictures and data received form weather satellite, and carefully determine what kind of weather is moving toward us.

Safety Rules

1. Never touch a switch with wet or damp hands.

2. Never poke around inside a radio or television set if it is switched on.

3. Never pull the chain of light bulb if you are standing on a wet floor.

4. Never touch a broken utility pole wire during or after a storm, or even when the sun is shining. Call a police man or a fireman.

5. Never touch an electrical appliances, switch,radio, or television set while in the bathtub or shower.

6. Never put electrical wires under carpets.

7. Never put anything but an electrical plug into a wall socket. Don't connect more than two appliances to a plug.

8. Never Remain in a lake during a thunderstorm.

9. Never remain under or near a tree during lightning-thunder storm. Get away from the tree lie flat on the ground.

How Can You Make a Horseshoe Electromagnet?

You will use:

     Long, thin bolt (or U-Bolt)
     Insulated copper wire
     Dry Cell
     Switch
     Small nails paper clips

Do this: 

1.Wind several layers of wire around one arm, then other, of a  U-Blot. (Such a blot, if unobtainable, may be made by bending a long thin bolt into a U-Shape, using a vise)

2.Strip the insulation form the ends of wire.

3.Connect one end of a  piece of wire to one terminal of the dry cell, and the other end to the terminal of the switch.

4.Connect a second piece of wire between the dry cell and the switch.

5.Close the switch. How many paper clips or nails can you pick up your horseshoe lectromagnet?

6.Open the switch. What happens? Try this several times.

Why it works:

     We already know why an electromagnet works.

     We are now able to take advantage of an electromagnet shaped like horseshoe?

     We are now able to take advantage of magnetism produced in both ends,  or poles, of both electromagnet. When both poles are near each other, we get up twice the strength that a straight bolt gives- if the number of turns of wire is the same on each side.

How to Make an Electromagnet?

You will use:
     Lantern dry cell
     Wire
     Switch
     Large Nail
     Small nails or paper clips

Do this:

1.Wind about ten turns of wire around large nails.

2.Strip the insulation form the end of the wire.

3.Connect one end of the wire to one terminal of a dry cell, and  the other end to a terminal of the switch.

4.Prepare second wire. Connect this wire to the other terminal of the dry cell and the other end of the switch.

5.Now close the switch, and try to pick up paper clips. Open the switch, and the small nails or paper clips fall.

Why it works:

     Electricity from one part of the dry cell flows through the many turns of wire back into the dry cell.

     When electricity flows through a wire,  the wire has magnetic power around it. If the wire happens to bein the form of coil, the magnetism is even stronger.

     An iron nail inside the coil become a magnet. This is true only so long as the electricity is flowing in the circuit. It is a magnet when you want it to be.

How to Make a Switch?

You will use:

     Electric lantern cell
     The bulb with wire attached that you just made
     Bell wire
     Strip of metal
     Block of Wood
     Nails
     Hammer

Do this:
1.Take a piece of metal 4 inches long and 1 inch wide. You can cut it form a tin can if you are careful not to cut yourself. Use the kind of scissors called  tin snips. Wear gloves.

2.Nail one end of the metal strip of the block wood. under the end of the metal.

3.Do not hammer either nail all the way down in the wood.

4.Bend the free end of the metal strip upward so that it is not resign on the nail beneath it.

5.Now you have a switch.

6.Connect one end of a length of wire to either terminal of a dry cell. Connect the other end of the wire to nail under free of the metal strip.

7.To connect a wire to the lantern cell, just twist the bare end of the wire around of the strips on the top of the cell.

8.Be sure to scape the insulation off ends of all the wires you see.

9.Using the lantern-bulb-and-wire-device you just  made, connect one end of wire attached to the bulb to the other terminal of the dry cell.

10.Connect the other end to the nail holding the strip of metal in place.

11. Now place the switch

12.If you have made all the connections right, the circuit is loaded, and the bulb will light.
13.Don't hold the switch down for more that few seconds. The dry cell will wear out.

14.Save this switch. You will probably use it many times.

15.A switch is a convenient way to open and close a circuit. It is easier that connecting and disconnecting wires.

16.Use your switch only with a dry cell. Don't try to use switch with any household electrical appliances or lights. YOU MAY BE KILLED.