Paper Topic:

Science

1 . Explain why earthquakes happen . Include the most venerable areas

According to the theory of plate tectonics , the earth 's crust is formed by a number of large plates that move very slowly in various directions on the earth 's surface . Most earthquakes occur near a boundary between two plates . As one plate pushes past or over another , great stresses build up in the rock along the edges of the plates because friction prevents them from sliding past each other . Eventually the stresses become great enough to rupture the rock . The edges of

the plates slip a short distance in opposite directions , causing an earthquake . The greater the stresses that have built up , the greater are the results of earthquake

2 . Describe the factors that cause a volcano to erupt

The hot , melted rock - or magma - lies deep inside the earth . The magma is squeezed up through the crust . Sometimes , the magma is forced up through the volcano , and the volcano erupts . When a volcano erupts , it can hurt people and damage property . Hot lava that flows down a volcano can burn homes . Moreover , scientists look for waning signals to predict when a volcano will erupt . Small earthquakes near a volcano might mean that magma is rising inside . A bulge on a volcano also might mean that the volcano is about to erupt

3 . Why is static electricity dangerous ? Why does it happen ? How can you control it

Most electrical systems consist of many charged articles , each of which exerts an electrical force on all the other charges , and vice versa Suppose for a moment that you could borrow all the electrons from a friend 's body and put them into your pocket . The mass of the electrons would about 20 grams . With no electrons , your friend would have a huge positive charge . You , on the other hand , would have a huge negative charge in your pocket . If you stood 10 m from your friend , the attractive force between the two of you would be about 1032 tons - more than 100 ,000 times greater than the gravitational force between the earth and the sun . Obviously , your pocket would rip off long before you had gathered even a tiny fraction of your friend 's electrons

4 . What is the difference between wattage and voltage related to appliances you use at home ? Voltage is a measure both of electric potential difference and of the electromotive force produced by a potential difference . Home power lines supply either 110 to 120 volts (for ordinary use ) or 220 to 240 volts (for such appliances as electric ranges and clothes driers . On the other hand , watt is a measure of electric power . Light bulbs and appliances are usually marked with the number of watts they require . The normal 115-volt , 15 ampere household circuit can safely handle electrical devices drawing a watts

5 . What is the difference between AM and FM radio waves ? Why do they work the way they do

In AM , the frequency of the...

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