QUESTION: Who proved that lightning was electric?
In 1752, the American scientist Benjamin Franklin determined to find out if electricity and lightning were connected. He carried out a very dangerous experiment. He took a kite and attached to it a metal rod. Then he tied the end of the kite string to a door key and went out into a thunderstorm. When he flew the kite into a thunder cloud, he saw sparks from the cloud passed from the kite down the string to the key. Never try this experiment yourself.
After this, Franklin made and tested the first lightning conductor. Today, all tall buildings are fitted with lightning conductors, which attract lightning more readily than the buildings. The connecting cable safely carries the electricity to the ground, preventing damage to the building.
QUESTION: Who made the first battery?
Alessandro volta (1745-1827) was an Italian scientist interested in electricity. In 1799, Volta used zinc and copper discs seperated by damp paper to make a 'cell' that produced an electrical current. By standing several cells in a pile, He discovered that he could produce a stronger current. Volta improved his 'voltaic pile' by using acid or salt solution instead of water to moisten the paper. He made the first battery.
QUESTION: What is a magnet?
A magnet is a piece of metal with the power to attract other sunstances. Iron and steel make good magnets. A magnet has two poles, north and south, near to its ends. Unlike poles (north and south) attract each other, just as opposite (+) and (-) electrodes do. Like poles (north and south) repel each other. Try putting two bar magnets together and watch waht happens. Can you tell which are the magnets' like poles?
QUESTION: Who discovered electromagnetism?
In 1820 a Dane, Hans Christian Oersted, discovered the magnetic effect. He was working with a battery and an electrical circuit, when he noticed that every time
he bought a wire through which current was flowing near a magnetic compass, the compass needle jumped. When he disconnected the wire from the battery, the compass needle jumped again. Oersted's discovery that magnetism and electricity were closoely connected, and that one could produce the other, was of immense scientific importance.
QUESTION: How does a simple dynamo work?
A dynamo is a generator that turns the mechanical energy into electrical energy. Its has an armature ( a coil able to spin on its axis) positioned between the poles of a magnet. When the armature turns, a current flows in the coil each time it crosses the force field of the magnet.
An electric motor works in the opposite way to a dynamo. It turns electrical energy into mechanical energy. When the current is passed through the coil, the armature rotates and keeps moving for as long as the current continues to flow.
QUESTION: Where does electricity come from?
The electricity that we use is made by giant generators, or dynamos, in power stations. A thermal power station converts heat into electricity by burning fuel to boil water to produce steam. The steam drives turbine generators. The fuel may be oil, coal or nuclear fuel (uranium). A second kind of power station uses the energy of moving water to drive the generators and is called a hydroelectric power station.
QUESTION: How does a fuse act as a safety device?
A fuse cuts off the electricity supply in a circuit when something goes wrong. Inside the fuse is a thin wire, able to carry a safe amount of current but no more. If an electrical appliance overheats it will start to use more electricity. The thin wire in the fuse (usually in the plug) heats up and melts. This breaks the circuit and cuts off the electricity.
QUESTION: What makes a light bulb glow?
The thin wire, or filament, inside a light bulb resisit the flow of current through it. When electricity is passed through the bulb, the filament becomes hot and glows brightly. To prevent the filament burning away completely, the glass bulb is filled with a mixture if inert gases (usually argon and nitrogen). The filament in most light bulbs is made of tungsten.
QUESTION: How do 'electronic eyes' work?
When light strikes certain substances, an electrical effect is produced. This electricity is called photoelectricity. The 'magic eye' that automatically opens door as you approach, or operates a burglar alarm , is worked by photoelectricity. A beam light shines on a photoelectric cell. When the beam is interrupted (by someone walking through it) the cell activates an electrical circuit. The circuit may start a motor open a door or (in a burglar alarm) set off a bell.
QUESTION: What is an integrated circuit?
An integrated circuit is a complicated arrangement of transistors and other components on a single piece, or chip, of semiconductor material. The first one was made in 1958. Making circuits smaller and smaller allows an amount of electronic power to be contained in a tiny space. HUndred of electronic components can be fitted into an integrated circuit the size of aletter in this sentence.
QUESTION: Why do microchips work so quickly?
Inside a microchip, the components are crammed together into a very tiny space. Electricval charges can move between them in almost no time at all, sao the chip does it work at amazing speed.
