Test # 299 [26-Apr-2017]

With whose help was the revolt at Avadh against the British Administration put down in 1857 ?

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  • Electricity

    Types of electricity

    There are two types of Electricity, Static Electricity and Current Electricity. Static Electricity is made by rubbing together two or more objects and making friction while Current electricity is the flow of electric charge across an electrical field.

    Static Electricity

    Static electricity is when electrical charges build up on the surface of a material. It is usually caused by rubbing materials together. The result of a build up of static electricity is that objects may be attracted to each other or may even cause a spark to jump from one to the other. For Example rub a baloon on a wool and hold it up to the wall. Before rubbing, like all materials, the balloons and the wool sweater have a neutral charge. This is because they each have an equal number of positively charged subatomic particles protons and negatively charged subatomic particles electrons. When you rub the balloon with the wool sweater, electrons are transferred from the wool to the rubber because of differences in the attraction of the two materials for electrons. The balloon becomes negatively charged because it gains electrons from the wool, and the wool becomes positively charged because it loses electrons.

    Current Electricity

    Current is the rate of flow of electrons. It is produced by moving electrons and it is measured in amperes. Unlike static electricity, current electricity must flow through a conductor, usually copper wire. Current with electricity is just like current when you think of a river. The river flows from one spot to another, and the speed it moves is the speed of the current. With electricity, current is a measure of the amount of energy transferred over a period of time. That energy is called a flow of electrons. One of the results of current is the heating of the conductor. When an electric stove heats up, its because of the flow of current. There are different sources of current electricity including the chemical reactions taking place in a battery. The most common source is the generator. A simple generator produces electricity when a coil of copper turns inside a magnetic field. In a power plant, electromagnets spinning inside many coils of copper wire generate vast quantities of current electricity. There are two main kinds of electric current. Direct DC and Alternating AC. Its easy to remember. Direct current is like the energy you get from a battery. Alternating current is like the plugs in the wall. The big difference between the two is that DC is a flow of energy while AC can turn on and off. AC reverses the direction of the electrons.

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