Electricity Test - 20

The commercial unit of electrical energy is $$kilowatt-hour\ (kWh)$$, commonly known as $$unit$$. $$1\ kW h = 1\ unit=3.6 \times 10^6 J$$. Electricity bills are calculated in the units of energy consumed.

Electric fuse work on the principal of heating effect of current . fuse wire is a wire of high resistance and low melting point. when very large current will pass through it, heat will be generated which will melt the fuse wire and break the circuit.By using electric fuses in home we can protect the home appliances from damaging by large amount of current.

Fuse wires are used to save the home appliances from damages by large currents. so they are made up of such materials which have high resistance and low melting point so that they can melt down when unexpected amount of current is passed through . For this work either tin metal or tin-lead alloy will be appropriate because alloys have high resistance and low melting point.

Any charged object - positive or negative, conductor or insulator - creates an electric field that permeates the space surrounding it.  So charges are on the outer surface of the conductor.

Also, since conductors allow electrons to be transported from particle to particle, a conductor always distribute its charge until the overall repulsive forces between the excess electrons is minimized. Hence no charge inside the conductor.

Components connected in series are connected along a single path, so the same current flows through all of the components. The current through each of the components is the same, and the voltage across the circuit is the sum of the voltages across each component. In a series circuit, every device must function for the circuit to be complete. One bulb burning out in a series circuit breaks the circuit. A circuit composed solely of components connected in series is known as a series circuit.
The total resistance of resistors in series is equal to the sum of their individual resistances. Hence, the Equivalent resistance is more than the individual resistances because a sum is taken of all the individual resistances. That is, $${ R }_{ total }={ R }_{ 1 }+{ R }_{ 2 }$$. The current is given as $$I={ I }_{ 1 }={ I }_{ 2 }$$.
Below is the diagrammatic representation of 2 resistors $${ R }_{ 1 }\quad and\quad { R }_{ 2 }$$ connected in series.

Equivalent resistance is given by:
$$\dfrac { 1 }{ { R }_{ eq } } =\dfrac { 1 }{ 3 } +\dfrac { 1 }{ 6 } =\dfrac { 1 }{ 2 } \\ \quad \\ { R }_{ eq }=2\Omega $$

The electrical conductivity of matter is dependent upon the atomic structure of the material from which the conductor is made. In any solid material, such as copper, the atoms which make up the molecular structure are bound firmly together. At room temperature, copper will contain a considerable amount of heat energy. Since heat energy is one method of removing electrons from their orbits, copper will contain many free electrons that can move from atom to atom. When not under the influence of an external force, these electrons move in a zigzag manner within the conductor. This movement is equal in all directions so that electrons are not lost or gained by any part of the conductor. When controlled by an external force, the electrons move generally in the same direction. The effect of this movement is felt almost instantly from one end of the conductor to the other. This electron movement is called an ELECTRIC CURRENT.
Some metals are better conductors of electricity than others. Silver, copper, gold, and aluminum are materials with many free electrons and make good conductors. Silver is the best conductor, followed by copper, gold, and aluminum. Copper is used more often than silver because of cost. Aluminum is used where weight is a major consideration, such as in high-tension power lines, with long spans between supports. Gold is used where oxidation or corrosion is a consideration and a good conductivity is required.
Hence, copper is a good conductor of electricity.

The fuse consists of a porcelain base on which two metal contacts are fixed. The incoming and outgoing phase wires are connected to these metal contacts. Porcelain made fuse carrier used for holding the fuse element or fuse wire. This porcelain made fuse carrier is inserted to the porcelain base for connecting a load side circuit to source side circuit. The main advantage of this type of fuse is that, the fuse carrier can be removed from the fuse base without any chance of coming in contact with the live part of the circuit.

Equivalent resistances is less than either of the two resistances when they are connected in parallel.
Components connected in parallel are connected so the same voltage is applied to each component. In a parallel circuit, the voltage across each of the components is the same, and the total current is the sum of the currents through each component. A circuit composed solely of components connected in parallel is known as a parallel circuit.
To find the total resistance of all components, the reciprocals of the resistances of each component is added and the reciprocal of the sum is taken. Hence, the Total resistance will always be less than the value of the smallest resistance. That is, $$\dfrac { 1 }{ { R }_{ total } } =\dfrac { 1 }{ { R }_{ 1 } } +\dfrac { 1 }{ { R }_{ 2 } } \quad that\quad is,\quad R={ { R }_{ total } }^{ -1 }$$. The voltage is given as $$V={ V }_{ 1 }={ V }_{ 2 }$$.
Above  is the diagrammatic representation of 2 resistors $${ R }_{ 1 }\quad and\quad { R }_{ 2 }$$ connected in parallel.

The connection wires are made of copper. 
Copper is a good conductor of electricity as it allows the electricity to flow through it easily. Copper as a connecting wire has very low electrical  resistance. Copper combines several properties that have traditionally made it preferred for most electrical wiring. It provides good contact surface, is ductile (is easily bent repeatedly without breaking) and it is not very expensive and is easy to manufacture.