Thursday, April 25

Elements of a Communication System


Communication system is used to conveying a message from one person to other. By means of an information is the attach which holds people jointly. A communication system is known as grouping of processors and hardware used to bring about the transfer of message through communication. This system having some elements for transfer the signal from source to destination.

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Communication Systems:

A communication system is known as grouping of processors and hardware used to bring about the transfer of message through communication. This process of a system allows us to take total unit.

An energy is need to start the system. The control mechanism regulates the process. That is, it manipulates the message input into whatever form is necessary. The result of this method is the appearance of message in a form which will permit us for communication to take place.

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Elements of communication systems

Let us see about elements of communication systems,


It is used for modulation and coding the original signal.
In communication system elements, it is used to converting an electrical signal into a form which is comfort for transmission on the physical channel or transmission medium.


In communication system elements, the communications channel is known as a communication medium.
It is used to send the signal from the transmitter to the receiver.
The Receiver:

In communication system elements, It is used for demodulation such as decoding the signal from channel.
The receiver is used to recover the message signal enclosed in the received signal.

In communication system elements, noise is produced at transmitter due to two process
1. Natural resources 2. Manmade

By nature, such as radiation from sun By manmade, noise made from like vehicles.
This noise can be reduced by using filter.

Wednesday, April 24

Initial Velocity

Let us start with the difference between velocity and speed. It is quite obvious after all the discussion about vector and non vector quantities. Speed is basically a measurement with no direction. In case of velocity we also consider direction.

Velocity can be of two types: initial velocity and final velocity. When the object starts its motion then we can say that the initial velocity is zero as it has just started from rest. Similarly we can also consider int. velocity as some constant value. Let us take an example of a car starting from rest and attaining a velocity of 50 km per hour in 1 hour time period.

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So here we can say that the int. velocity of the car is zero and the final velocity is 50 km per hour, directed northwards. Here mentioning the direction is very important as velocity is all about direction, it being a vector quantity.

Let us now discuss Initial velocity formula. We have 3 equations of motion that have a reference to int. velocity and hence can be used for its calculation.
They are as follows:
V = u + a t ------------ > (1)
Here v is the final velocity
U is the int. velocity
A is the acceleration
T is the time period.
So u = v – a t
Also the second equation is
S = u t + 1.5 a t^2 - - - - - - >(2)
Here s is the distance covered in time interval t.
A is the acceleration
We also have a third equation for calculating velocity. It is as follows:
V^2 = u^2 + 2 a s - - - - - - -> (3)

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Here v is the final velocity and a is the initial velocity.
All these are initial velocity equation. We can also say that u^2 = v^2 – 2 a s - - - - - - - > (4)
Let us take a real world example to clear the concept. Let us assume the final velocity of the car is 50 m per sec and the time taken to complete the journey is 2 hours. Also the acceleration is 10 meter per second square. So now using first formula we will try to calculate the initial velocity.
Hence v = u + a t
Or 50 = u + 20
U = 50 – 20 = 30 m per sec


Newton’s first law of motion explained that if an object is in rest then it is said to be in rest and when it is moved then it is in motion, so it proves that all objects have natural tendency to be in rest, they resist their motion.

So the property of any object to stop its state of motion is known as inertia. This word can also be described in terms of a resistance in the motion of object. So this is the particular property of an object to stop any alteration in its motion. Please express your views of this topic Angular Acceleration Problems by commenting on blog.

It is basic of classical physics and use to know about the matter’s motion and the effect of applied forces on the motion of matter. In general words, this can also be explained as the resistance to alter in the value of the velocity or the momentum. There is not any particular theory that describes the source of (In).
The law of inertia states the same definition of (In). This explains it as the specific property of any object to stop any change in its motion. As Newton's states that for the movement of an object, the external force is required like friction or gravity.

So first this concept was explained with taking the example of earth as the earth also revolves around the sun. And if the body is moved on a flat surface in a given straight direction then it is continued with its speed with the same direction unless disturbed.

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The Inertia Equation can be written with the use of mass and radius of moving body. So the formula for the (I) may be generally expressed as; I = k m r^2; where m is the mass of body, r is the distance travelled, and k is (I) constant which depends on the shape of the moved body.
For example; if we discuss about the thin-walled hollow cylinder, then the momentum of a thin-walled hollow cylinder is like the point mass. So it can be expressed as; I = m x r^2  and k is equal to one as it is taken one for point mass, where m is hollow’s mass and r is for distance.

Here we are taking two distances; one is the distance between axis and the thin walled hollow and ro is the distance between axis and outside hollow. So for the hollow cylinder: I = 1/2 m (ri2 + ro2). But for a solid cylinder, it is equal to the; I = 1/2 m r^2 (3c).
We can also measure the Product of Inertia by measuring (I) of a moving body in two different axes.  As it is measured by the mass of an object, so the Units of Inertia is kgm2. This is Inertia Units in SI system.

Uses of Solar Energy

Introduction to solar energy

Sun is the primary source of heat and light, all living things need sunlight for it's survival, we are getting various forms solar radiations like UV radiations, gamma radiations,infraded radiations etc, solar energy can be used as various other forms of energy,so, we can use solar energy as alternative sources of energies.In 21st century, obviously we should depend upon alternative sources of energy,because some sources of energy are  limited in nature, so it is known non-renewable sources of energy like fossil fuels,by considering these situations, we should depend upon renewable sources of energy like solar energy.

Solar energy  be used to run vehicles, in solar lights,in solar traffic signals, in solar water heaters, in solar cookers,plants prepare food by the process of photosynthesis using solar energy etc.

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Applications of solar energy

Solar water heaters

Solar water heaters are really boon to the mankind, which conserves other sources of energy and it is eco friendly, in solar water heater it has solar panels consisting of photovoltaic cells,semi conductors, which are made out of silicon chips. these silicon chips absorb solar energy and help in heating up the water, there is an arrangement of inlet and outlet for water. water has to pass through in these set up of solar water heater.

Solar heating system composed of solar thermal collectors, a water storage tank, interconnecting pipes and a fluid system to move the heat from the collector to the tank, so in this process heating up the water by using direct sunlight, no electricity is required.

we can use this solar water heating system for various purposes like under floor heating, heating swimming pools, energy input for space heating or cooling, storing solar energy for future like for winter season by storing solar heat in the ground.

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Solar vehicles

Solar energy can be used to run vehicles like solar bicycle, solar cars, solar autos etc, these vehicles proved and it may replace our existing needs to run vehicles ,basically a solar vehicle is a electrically powered by solar energy. the photovoltaic cells absorb solar energy, then which converted to electrical energy.

Thursday, April 18

Kinds of Forces

Introduction to kinds of force:
Sir Isaac Newton was the first who gave an exact definition of force.He stated that :

Force is the external agency applied on a body to change its state of rest and motion.

There are four basic kinds of forces in nature. They are

Gravitational force
Electromagnetic force
Strong nuclear force
Weak nuclear force
Lets see a brief explanation of the different kinds of forces.

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Explanation of gravitational and electromagnetic forces:

Gravitational force:

It is the force between any two objects in the universe. It is an attractive force by virtue of their masses. By Newton's law of gravitation, the gravitational force between tow bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. Gravitational force is the weakest force among the fundamental forces of nature but has the greatest large- scale impact on the universe. Among the basic force only gravity works universally on all matter and energy, and is universally attractive.

Electromagnetic force:

It is the force between charged particles for example the force between two electrons, or the force between tow current carrying wires. Electromagnetic forces for like charges is repulsive and for unlike charges is attractive. The electromagnetic force obeys inverse square law. It is very strong compared to the gravitational force. It is the combination of electrostatic and magnetic forces.

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Explanation of strong and weak nuclear forces:

Strong nuclear force:
It is the strongest of all the basic forces of nature. It, however, has the shortest range, of the order of 10-15 m. This force holds the protons and neutrons together in the nucleus of an atom.

Weak nuclear force:
Weak nuclear force is important in come types of nuclear process such as `beta` -decay. This force is not as weak as the gravitational force.

Wednesday, April 17

Average Speed

Average Speed

When a body moves, sometimes it accelerates and other time it decelerates due to the traffic congestion on the road, so the speed of the body is not constant over the whole journey and keeps on changing with respect to several factors.
If we need to calculate the speed for the entire journey it is calculated by finding the total distance travelled and the time taken to travel it. This is known as the average speed of the body for the journey it has travelled.

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Average Speed Formula

The formula for finding the avg speed is;
Saverage = (total distance travelled / total time taken);
where, total distance travelled is equal to the distance between the source and destination of the body and the total time is the time taken to move between the source and destination by the body.

Formula for Average Speed
The formula of avg speed is as follows;
Saverage = (DTotal / TTotal);
DTotal = Total distance travelled the body;
TTotal = Total time taken in travelling the distance DTotal by the body.

Average Speed Definition

The avg speed is defined as the average of the speed of the body over the total distance travelled by it. The body might be travelling at different speed over the portion of the total distance but it maintains the avg speed for the entire journey as constant. The avg speed can be obtained by dividing the distance travelled by the object by the time taken to the distance.
Average is helpful in identifying the speed of the body when it is travelling at different speeds for the different portions of journey. It is used to calculate the speed of the object in varying traffic conditions.

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What is Average Speed

To understand the average let us take an example. A truck is climbing the hill at the speed of 15 km/hr for 1 hour and then it started to slow down as the hill is steeper and travels at 5 km/hr. After 2 hours the truck started to climb down the hill at the speed of 25 km/hr for 1 hour to completely come to the plain.
In this journey as we see the truck is moving at different speed at different time and hence it is difficult to identify the speed of the truck but if divide the total distance travelled by it with the total time it took to travel the total distance then what we obtain is the avg speed.
In this example the avg speed is
Avg speed = 50 / 4 = 12.5 km/hr.

Angular Displacement

Angular Displacement

Displacement is known as the change in the position of body or object with respect to a point of reference. Displacement is a scalar quantity. Similarly when an object or body changes both the position and angle then it’s displacement is calculated as angular displacement.
Angular-displacement is the change of the angle and the position of the body with respect to its initial position and angle.
Although displacement has magnitude and direction still it is a scalar quantity and not the vector quantity.

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Angular Displacement Formula

The angle of displacement is always measured in radians, since it is the change in the angle of the body with respect to its initial position.
The formula to find angle of displacement is given as;
Angular-Displacement = ???
??? = angle between the initial position of body to its final position.

How to Find Angular Displacement?

For finding angle of displacement, we need to follow these steps;
1. First obtain initial position of the body;
2. Obtain the final position of the body;
3. Find the angle between the two positions;
4. The angle is the measure of the angle of displacement.

In case if the linear displacement and the radius of curve is given then use the following equation to obtain the angle of displacement;
Angular-Displacement = ??? =
s = linear displacement; and
r = radius of curve through which the body rotates.

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Example of angular displacement:

A car is moving with the speed of 40 km/h on a curved surface having a diameter of 50 cms. Find the angle of displacement of the car along the curve at time t = 10 sec, 20 sec and 50 sec?
As given in the question above we need to first identify the linear displacement at different time and then using the relation between the linear displacement and angle of displacement we will find the angle of displacement of the car at different times.
For time t = 10 sec;
s = 40 * (10 / 60 * 60) = 111.11 meters;
so the angle of displacement at time t = 10 sec is;
???t=10 = 111.11 / 0.5 = 222.22 radians

For time t = 20 sec;
s = 40 * (20 / 60 * 60) = 222.22 meters;
so the angle of displacement at time t = 20 sec is;
???t=20 = 222.22 / 0.5 = 444.44 radians

For time t = 50 sec;
s = 40 * (50 / 60 * 60) = 555.55 meters;
so the angle of displacement at time t = 50 sec is;
???t=50 = 555.55 / 0.5 = 1111.11 radians

Wednesday, April 10

Man Landing on Mars

Introduction to man landing on mars:

Mars is the 4th planet from the sun.  It is called the "Red planet" because of its reddish appearance. Mars have similar surface feature compared to our earth and moon such as volcanoes, valleys, deserts, polar ice caps and the impact craters of the moon.The seasonal cycles of mars as well as the rotational period is very much similar to the Earth. Mars has two moons, Phobos and Deimos. Mars was formed around the same time as the Earth. Both Mars and earth are rocky planets. Mars diameter is almost half the diameter of the earth, a far thin atmosphere and desert-like surface too. Mars has the same land area as the Earth as we know that our earth's surface has only a quarter area of land, the remaining being water.

Exploration of Mars

The Soviet Union, United States of America, Europe and Japan are active participants in the space exploration program which involves the exploration of the planet Mars. Dozens of robotic spacecraft, including rovers, landers and orbiters have been launched towards Mars since 1960s. These missions were carried out in order to gather data about the planet's current conditions and history and also whether any  possibility for the sustenance of human life on the planet.

After many attempts of landing on Venus, Venera-7 landed on Venus in the year 1970. Another, Mariner-10 has also passed by Mercury and sent back pictures of the mountains and the craters there. Mars is even more interesting and both the Russians and Americans have sent space crafts to it. The Viking, launched by the Americans made gentle landing there in 1976, sending back pictures direct from the surface. Jupiter and Saturn have also been bypassed. Both Voyager-I and 2 sent back clear pictures of Jupiter's clouds and moons and the rings of Saturn whereas Viking I and II sent back data about the Martian atmosphere and soil apart from sending images of Mars.

Meanwhile the USA and the former USSR undertook a joint US-Soviet manned space mission called the Apollo-Soyuz Test Project. The Apollo Spacecraft carrying three astronauts and the Soyuz-19 Spacecraft, carrying two cosmonauts were launched separately on 15th July 1975. Two days later, the spacecraft approached each other and docked in space. For two days, the crew conducted joint experiments and surveys. Many other probes were launched during the decade of the seventies. The space probe Pioneer-10 sent by USA explored the asteroid belt and took photographs of Jupiter from a close range.

The eighties have seen many significant developments in space science. Space shuttles were designed by the US. The space shuttle takes off like a rocket, flies like a spaceship and lands like a glider. Unlike an ordinary rocket it can be used again and again. The picture below shows a space shuttle Columbia gliding into land. This first space shuttle was launched in 1981.

Landing of Man on Mars

The permanent manned space station called Mir was launched by the Soviet Union in 1986. Since then many crew have manned this space station and conducted experiments in space.

The year 1997 marked the return to the red planet. For almost twenty years every Mars mission ended in failure. The two Russian Phobos crafts failed. The US Mars observer exploded as it prepared to enter the planet's orbit and the mighty Russian Mars' 96 craft did not escape from earth's atmosphere. Finally Mars path finder parachuted down to Mars and its new landing technology proved to be a success. A little six-wheeled river Sojourner, spent nearly three months analyzing Martian rocks before the battery went flat. More missions have been planned, to bring rock samples to earth and even to land first human on Mars.

Barack Obama the "President of the United States of America"  truly believes that in the next 20-25 years, humans can be sent to orbit Mars followed by a safe landing and shall return safely back to earth. A number of nations and organisations have long-term intentions to send Humans to the planet Mars. The United States  has a number  of missions currently exploring Mars. The European nations has sent robotic probes and has long-term plans to send humans too. Russia, Japan and China are keen in sending humans to Mars too.

"Its high time the beings in outer space stop chomping on their Alien bars,

Because the humans are bound to land on MARS"

Used Appliances

Introduction to used appliances:

Do you want that stunningly looking LED home theater television at Joe’s as yours? It’s not at all a big deal to own it. Just pay a visit to your nearest used appliances selling outlet. It won’t kill your urge to own one. I swear.

Second hand selling market is a trend everywhere around the globe. Anything is available for a reasonable price with reliable servicing offers. When you sell your old buggy television in order to get it exchanged with a new one, just remember one thing. Someone else is there to buy that product for a big amount of money for the same product that you just abandoned for a cheap price.


It’s a real fact that many families with low living standards are enjoying their lives using these appliances that you consider as an e-waste. The stores that accept the used appliances may have a thorough check up on the products to find any inappropriate things that may cost as unfavorable while reselling it. They might give some advertisements carrying fancy words that the products they are selling are gently used, old reliable goods etc. It’s all are the methods to catch the attention of the middle class customers. They all win in that also.

Selling of used appliances

The products are sold with a label of gently used goods. So through this label they can gain the trust of the customers. The customer comes to a used appliances shop to buy a product which he already knows much about. So the shop owner cannot play tricks on him much like he did while selling a new product. But he can hide any faults to some extent. For example, there is a CRT television displayed to get sold. The television might be having some faults like failing of picture tube to display after 10 minutes or like that. This type of faults can be easily hidden from a customer. Also the shop owner can argue and win that it is something that went wrong with the customer’s household electric connection that caused damage to the picture tube.

The used appliance market is a safer place to bargain if you are confident about the reliability of the product. Also you will get better service for that too. Most shops offer 30 days warranty for their products.

Universe Solar System

Introduction to Universe Solar System:

Family of the sun is given the name solar system. Sun is the centre of solar system. Nine planets are revolving around the sun in the elliptical orbits. The distnace of the planets from the sun and their velocities keep on changing as they revolve around the sun.

Some other heavenly bodies also revolve around the planets and are called satellites. These are also called moons of the planets. Some other heavenly bodies revolving around the sun are asteroids, comets and meteors etc.

Let us discuss about universe solar system and its objects in detail:

Description of universe solar system:

1. Sun:

- It is the nearest star that we can see.

- It shines of its own.

- It is also called luminous body of our solar system

- The mass of the sun is 1.99 x 1030 kgm and its diameter is 1.4 x 109 m.

- It is about 109 times the diameter of the earth.

- The average distance of the sun from earth is about 1.496 x 1011 m, which is called one astronomical unit (A.U.). It is a unit used for the measurement of large distances.

- Sun rotates about its axis from east to west and completes one rotation in approximately 30 days.

2. Planets:

- Planets appear to be bright and do not emit light of their own. They reflect light of sun.

- These heavenly bodies revolve around the sun in elliptical orbits.

- Nine planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. These planets are written in the order of increasing distance from the sun.

Some other Objects in Universe Solar System:

3. Asteroids:

- Asteroids are very tiny planets (pieces of large planets) revolving around the sun between the orbits of Mars and Jupiter.

- Like regular planets, asteroids also revolve in elliptical orbits nearly in the same plane as that of the earth.

- The largest asteroid is called Ceres having radius  350 km and the smallest one is having radius only 50 m.

4. Comets:

- Comets are made up of rock like material surrounded by large masses of easily vapourised substances like water, ammonia and methane.

- The comets revolve around the sun in elliptical orbits.

- As comets come closer to the sun, the water vaporizes due to heat of sun.

- The light of sun exerts a pressure on these vapours and forces them to move away from the comet in the form of a tail.

- Edmund Halley discovered a comet in 18th century named as Halley's comet. This comet completes its orbit around the sun in 76 years. It can be seen in the sky after every 76 years. Last, Halley's comet was seen from earth in April 1986.

5. Meteors:

- When comets break while approaching the sun, the smaller pieces become visible.

- When they enter earth's atmosphere and heat up due to friction, they catch fire while moving towards earth.

- Therefore, we see a streakof light during night.

- These 'shooting stars' are known as meteors.

- They are of different sizes and weights.

- Most of them are in small sizes, and get completely burnt and do not reach earth. These are called meteors.

- Some heavy meteors landing on the earth are called meteorites.

- One of the biggest meteorites fell in Siberia on June 30, 1908.

Adding Sugar to Water

Introduction to adding sugar to water:

Sugar is a crystalline carbohydrate. It comes from sugarcane. It is sweet in taste. When added to the water, the sugar particles break down into smaller pieces. These small particles then arrange themselves together with the water particles and form a liquid solution..Sugar particle will no longer be visible with our naked eyes.

Sugar is soluble in water. When you add sugar to water and dissolve it volume of water before sugar is added is lesser than the volume of sugar in water. When we add sugar to water, the sugar crystal dissolves and it goes into the solution. Infinite number of sugar cannot be dissolved in a fixed volume of water. When as much sugar is dissolved, the solution is called saturated solution. The saturation point is different at different temperature .more sugar is held in a water, if the temperature is higher.

Adding sugar to water:

The size of the sugar crystal increases by the following process

1) Add sugar to the boiled water and stir it., till it dissolves.
2) Pour the solution in a jar and cover it with a waxed paper.

3) Dip a cotton string in a sugar solution, take it out, and dry it for few days.

4) The string after drying should be suspended in sugar solution and left undisturbed for seven days. at the end of seven days ,we will see that the size of a sugar crystal has grown in size with sharp edges and smooth faces. Dissolve more sugar to water on heating. by this solution becomes supersaturated. And the process of crystallization begins, once the heated solution cools down.

Explanation to adding sugar to water:

Add a pinch of sugar to water and feed a plant. That has wilted. And is not watered for a few days. the sugar helps the plants to get back to normal quickly. But this doesn’t always work. If the amount of sugar in the soil becomes too high, it promotes a higher incidence of fungi and bacteria. A typical fungus that thrives on sugar is yeast. Excess amounts of yeast causes an increase in the risk of an infection to plants and humans.

Thursday, April 4

Planet With Largest Moon

Introduction to planet with largest moon:

A solid heavenly body that revolves around the planet is called its natural satellite or its moon. For example, moon is the natural satellite of the earth because it revolves around the earth. Moons do not have their own light. They reflect the sunlight falling on them and therefore, appear shining. Except Mercury and Venus, all planets have their own  moons. In general, moons are much smaller than the planets. We can see the earth’s moon by unaided eye. The other moons of other planets were discovered after the invention of astronomical telescope and a large number of moons were discovered only after the spacecraft flew past them. The different moons have different features; some of them are earth’s like moon having large number of craters. Some of the asteroids have moon also. The asteroid IDA has also a moon. The planet Saturn has largest moon named as Titan.

Largest moon with planet:

Saturn is the second largest planet of our solar system. Saturn is known as the Jovian planet, because its structure is like Jupiter. Voyager explore the Saturn in 1980 – 81. Saturn is the sixth planet of our solar system. Saturn is the only planet whose rings are visible form the earth’s based optical instruments. The rings of the Saturn are formed by particles of ice and dust revolving around the planet. The particles in the ring having size in nanometers to meters.

Characteristics of the Planet with largest moon:

The density of the Saturn is less than the density of water. The atmosphere of Saturn mainly contains hydrogen, helium and methane. Saturn has 62 moons at present. Out of 62 moons, 53 are well named. Titan is the largest moon of the Saturn. The atmosphere of Titan is nitrogen rich as like earth in early years. Saturn is flat at poles so that it rotates very fast on its axis. Saturn takes 10 hours 39 minutes to rotate on its own axis and 29.5 earth’s year to revolve around the sun. The wind blows at very high speed on Saturn. The size of Titan is more than the size of planet Mercury.

Wednesday, April 3

Negative and Positive Wires

Introduction to negative and positive wires:

Let us first discuss about electricity, which can pass through the wires. There are two types of current, one is called the alternating current, which is used, in electrical mains and the other is called direct current, which is used, in the car’s light and in the radio. Direct current is obtained by the battery.  Let us discuss the wires, which carry the electric current.

Types of Negative and positive wires

Generally, there are three types of the wires:

Positive wire,
Negative wire and
Ground wire

In case of direct current, the positive wire is the wire, which carries 120 V. Negative wire is the wire, which has about 0 V. Ground wire is actually connected to the ground. Negative wires should be at zero potential or close to zero potential. It is the central point between the two phases of the electrical service coming to your house from the transformer on the electrical pole. Positive wire is the wire, which supplies the electric current to the electrical appliance. It is supplied to the devices in your home through a set of circuit breakers or fuses in older homes. It is wired directly to the outlets, and goes to the permanently installed lighting through the permanent wall switches. There is a standard colors in house wiring are: positive wire is of red color, negative wire is of black in color and the ground wire is of green in color.

Conclusion for negative and positive wires

Some of the devices in our daily life have only two flat prongs, and some have the third, round grounding prong. The two-prong devices are typically low current, low-power devices like lamps, bulbs, clock radios, can openers and the like. The third prong generally appears on higher-powered devices: washing machines, vacuum cleaners, televisions, computers, leaf blowers, drills, etc. This is usually done for safety reasons. This is also, why miswired outlets are dangerous: if the neutral and hot are reversed, the appliance will work just the same. However, if the appliance fails, the 'stray' energy remains under the 'top' insulating layer (next to the user), Not in the bottom one, putting the user at much greater risk. In older tools with metal cases, the user would actually get electric shocks in this event.