Category Physics

Fuses break the electric circuit when the current becomes very strong owing to any overload. As a result, the wires are never too hot, and a fire is prevented. In safety fuses, such as those used in cars or in screw-locking devices in homes, a thin wire inside the fuse melts when it gets heated by a very strong electric current. The fuse blows and must be replaced. In modern fuses, the circuit is broken with the help of an electromagnet, which ‘jumps out’ to break the circuit. When the fault has been fixed it is easily reset by pressing the switch.

Electricity travels from a place of high voltage to low voltage, just like water travels naturally from high elevation to low elevation. If the bird sits on a wire and also touches the ground, a path is created that allows electricity to travel through the body and to the place with no voltage. When electricity travels through the body of the bird in this fashion, electrocution takes place, and the bird dies. However, if the bird touches a single wire it does not get a shock because electric current passes through the wire instead of the bird. 

In direct current, electrons flow only in one direction, but in alternating current, electrons keep switching their directions. Due to significant advantages of alternating current over direct current, electrical power distribution is nearly all in the form of alternating current today. For many appliances, such as lamps, direction of flow of electrons does not matter; for others, such as computers, the flow needs to be uniform. Hence, a ‘rectifier’ is connected to a computer, which converts the alternating current into direct current.

European sockets provide electric current at 230 volts. Since, this voltage do not suffice to cover the large distance from the power plant to our homes, it is raised in the power plants with the help of transformers up to 380,000 volts. Locally, large substations or small ‘transformer houses’ transform the voltage to 230 volts. A transformer is like an electromagnet. The incoming high-voltage electric current generates a magnetic field in the coil. This permeates the neighbouring coil in the second electric circuit and generates a lower voltage: 230 volt.

By current we mean the flow of negative charge, i.e., the flow of electrons. Metals have lots of electrons. Hence, current flows in them, and they are good conductors. Substances such as air and glass are bad conductors. We need a source of power, such as a battery, to bring the electrons in motion so that a bulb can start glowing. The battery has a positive (+) and a negative (-) terminal. There are a lot of electrons at the negative terminal and only a few at the positive one. The flow of electrons from the negative terminal to the positive terminal is the current. It is measured in amperes (A). The greater the difference in charges between the two terminals, the stronger will be the flow of the current. This difference is known as the electrical voltage. It is measured in volts (V). 

Electricity plants convert the energy from the raw materials of the Earth into electrical current. This is done with the help of huge generators, which are driven by water, steam, or wind. Electricity is then distributed at a high voltage through cables laid in the ground or through overhead lines, on which often birds sit in swarms. Substations then produce electricity, which finally comes out of the sockets in our homes: 230 volts alternating current. However, many devices, such as computers, need direct current. Fuses protect us and our property from damages.