## The perfect sphere!

A priceless spherical object was created by Australian scientists with its raw material costing around 1 million Euros.

But why!

You might be wondering why would anyone invest such a large amount just to make a sphere! Well this sphere is an attempt to redefine a kilogram i.e SI unit for measuring weight!

To get into detail of why this sphere is created we need to know following facts:

1. A ‘meter’ is defined as the distance travelled by the light in (1/299752458) second

2.A second is dedined as “the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom” (at a temperature of 0 K).

From above examples it can be seen that these units are well defined and won’t change with time.

But then let’s see how a kilogram is defined:

1. Earlier a kilogramme was defined as the mass of a litre of water at 4 degree celcius.

2.Later it was replaced by a pure platinum cylinder and finally a platinum -iridium alloy (which is harder than pure platinum) was used as a standard.

Till now this cylinder which made of platinum-iridium alloy is used as a standard for kilogram.

What is the problem?

1. Kilogram is the only unit of measurement which is defined by a physical object!

2. This is kept at ‘International bureau of units and measurement’ under high security and under temperature control.40 more replicas of this cylinder was sent to different parts of the world as a standard for kilogram.
These sister object were brought together and it was found that their mass had changed. A deviation of around 50 micro gram was found in the weight and it was due to the change in the weight of platinum iridium alloy with time!

Kilogram is a very important unit as many derived units such as Newton ,joules ,watt etc depends on kilogram.Hence this drift in this unit is not acceptable.

How can the sphere solve the problem?

1. The sphere is made of only one isotope i.e Silicon 28

2. Hence it becomes possible to calculate the number of atoms present in the sphere which indirectly gives you the weight! It is similar to a perfect crystal!

3. Diameter of the sphere can be measured by laser. This gives us the volume.Density of atoms of silicon 28 isotope is accurately known .Hence by using Density=(mass)/(Volume) we can calculate atoms in the sphere.

Avagadros number is equal to number of atoms in 12 g of carbon 12.This is how avagadros number is defined.

Now using the sphere we can calculate a fixed value of Avagadros number which will be used to calculate a kilogram!

Interesting Fact!

The sphere mentioned above is so spherical that if this sphere is expanded to the size of earth then the distance between the highest peak and the deepest valley would be just 14meters

If you compare this with earth then the distance between highest peak and deepest valley is 19.8 kilometres!

If this sphere is able to bring down the error to 20 micro grams then it might be able to replace existing definition of a kilogram.

https://youtu.be/ZMByI4s-D-Y A priceless spherical object was created by Australian scientists with its raw material costing around 1 million Euros. But why! You might be wondering why would… Read more "The perfect sphere!"

## How Fitbits work ?

Fitbits have become very common nowadays. Even you might be having one with you. But do you know how it works?

Everytime you check your heart rate,steps,calories,etc have you ever wondered how it comes up with those data?

So keep reading and let’s uncover the secret behind fitbits.

## How fitbits Count steps?

Fitbits use a 3-axis accelerometer to determine the number of steps . Accelerometer converts movements into digital measurements.These measurements are then put into an algorithm that determines the number of steps you have covered.Basically a threshold distance is set.if the movement measures above the threshold then it is counted as a step.

We will have a separate blog on what accelerometers are exactly and how they work later on.

## How does it determine the distance covered?

Distance covered is basically equal to the number of steps multiplied by your stride length. An average stride length is already set in the device depending upon your age and sex.Steps are counted using the step counting algorithm.Since we have both the data distance can be easily calculated using the above mentioned formula.

When you keep your GPS on , then the distance is calculated using GPS itself else it is done by the formula mentioned earlier.

## How does it measure heart rate ?

Fitbits use a sensor called PPG to measure the heart beats.
It’s essentially testing how much red or green light it can see when looking at the skin on your wrist. Blood is red because it reflects red light and absorbs green light, so when your heart beats, there’s more blood flow in your wrist, and more green light absorption. Between heart beats, there’s less absorption of green light.

Now even though fitbits have become so popular , it doesn’t give accurate readings.Also these features except heart rate monitoring are incorporated in your smartphones as well.But still people find it cool and continues using it.

Fitbits have become very common nowadays. Even you might be having one with you. But do you know how it works? Everytime you check your heart rate,steps,calories,etc… Read more "How Fitbits work ?"

## What is Digital Marketing?

Marketing in simple terms, is the promotion of products or brands.Marketing can be done in many ways and one of the way is Digital Marketing.

Digital marketing is a type of marketing in which we use electronic media to promote products or services.It is also called online marketing, web marketing or internet marketing.Digital marketing was there from a long time but now it is the fastest growing and widely used type of marketing.

Digital marketing is a wide concept and it includes e-mail,RSS, voice broadcast, video streams ,blogging, instant messaging, pod casting and few more.

Digital marketing does not include traditional forms of marketing such as TV billboards,Banners ,radio broadcast etc.Digital marketing have instant reviews from customers and you can actually find out number of people who have actually seen your ads and also who have responded to your ads.Hence digital marketing is more versatile.

Why Digital Marketing?

Digital marketing provides you a larger scope to reach out your customer.

Let’s take an example

Suppose you have a shop which sells X item.Lets say you pick two options to promote your shop:

1. By using traditional methods such as banners, newspapers etc

2. By using digital marketing

In first case you are not aware of people who are seeing your ads.They might not be interested in products you sell.They might not be the right category of people you are searching for.For eg : Targetting men for women’s parlour! In short everything will be uncertain

While in second case you can use different digital marketing tools like adwords, Adsense , Facebook ads ,Instagram ads and many more tools to define who will be watching your ads ,their age,interests,location,time of watching ads and many more.There are many tools available which will be explained in upcoming blogs.Hence using digital marketing you can easily target more people using lesser money.

In short digital marketing provide you following advantages:

1. It makes targeting customer simple.

2. Increases you chance to hit the right customer

3. Cost reduction

5. Complete control of when to start and stop the ads

7. It helps you to control number of times same ad will be shows to the same customer.

8. Ease of customisation of ads

Apart from these there are many more parameters where digital marketing is far more better.Ofcourse there are some disadvantages but that depends on the type of product you wish to sell.

In upcoming blogs various digital marketing tools ,strategies,bidding etc will be explained

So stay tuned and keep reading!!!

Marketing in simple terms, is the promotion of products or brands.Marketing can be done in many ways and one of the way is Digital Marketing. Digital marketing… Read more "What is Digital Marketing?"

## Li ion Batteries |Charging|Protection

In a previous post we had a discussion regarding how a cell phone charger works . I hope that was informative enough. But a charger alone  cannot charge the LI ion batteries in your phones. They additional circuitry which is embedded inside your phone. Li ion batteries are not safe to play with and thus it also requires a special protection circuit. So today we will have a brief discussion on charging and protection of Lithium cells . So keep reading .

### Constant Voltage Constant Current Charging :

A lithium cell is charged using the principle of constant current and constant voltage.So lets see what this principle exactly is.The graph above illustrates the principle.

As shown in the graph , in the initial phase of charging , the current is kept constant and the voltage increases linearly with time. This phase is known as the constant current phase.This continues until the voltage reaches the maximum battery voltage. Once the voltage reaches the peak it remains constant and the current starts decreasing exponentially till cut off. This phase is known as the constant voltage phase.

The constant charging current can be set as per our requirements by making adjustments in the circuit. If you are using an Integrated Circuit for charging then you can program the charging current by varying a specific resistor value. TP4056 is an example of charging IC for a single lithium cell.

### Battery protection :

Here is one of the protection circuits that is used in order to protects lithium cells from damage by preventing battery operation at under voltage ,over voltage and over current conditions.

Lithium cells need to be handled with care or it can serious problems and thus it is necessary to protect these cells. But how does this circuit protect the batteries.

Let’s find out .

A battery may get damaged if

1. its voltage goes below a threshold voltage
2. Goes above a thresh voltage
3. Or it exceeds the current limit

The battery protection circuit is used to prevent the above scenarios.So let’s say the voltage has dropped below the threshold. In that case the IC detects it and pulls the DOUT pin low and thus inhibiting the discharge operation.This is because , the battery will be grounded only if both the transistors are on.But as one of these transistors is turned off the battery doesn’t get grounded and discharging stops.  Similarly ff over voltage condition occurs the COUT pin is pulled low and stops the charging. In case of over current ,the IC checks the voltage across the V- pin and if that exceeds the permissible value then the discharging is inhibited.

Dealing with a single lithium cell is not a big pain. But when you have multiple cells then the complexity increases. Also there is a concept called Cell balancing when it comes to multiple cells. All those will be covered in detail later on.

In a previous post we had a discussion regarding how a cell phone charger works . I hope that was informative enough. But a charger alone  cannot… Read more "Li ion Batteries |Charging|Protection"

## Giveaway results!!!

Hello guys,

We are happy to announce winner of our first giveaway!

For those who didn’t win this time , we promise you will get many more opportunities like this with better products and more quantity! Just keep reading and following us to stay updated with our new blogs and giveaway information!

WINNER:

Winner for this giveaway is Tuhin das! Congratulations to the winner!

You can now select any earphone mentioned on the website and it will be delivered to you! Thanks for participating!

Further details will be sent to you on your email id. For more information email us at neotechsters@gmail.com

Hello guys, We are happy to announce winner of our first giveaway! For those who didn't win this time , we promise you will get many more… Read more "Giveaway results!!!"

## Let’s code in python !!!

Now that you have python installed in your systems we are all set to start programming in python.

### So let’s begin !

In order to write a program/code you need an editor/IDE[Integrated Development Environment] to write on . So we will be using the python IDLE for now and later on we will switch to a better IDE where we will discuss the need to shift to a different IDE.

Today our aim is to get introduced to programming in python.So first of all open the python IDLE. Just search for IDLE and open the first option itself,

This slideshow requires JavaScript.

So this is the python shell where you can directly execute python commands.So let’s get started with the first python command.

We will first see how to print a statement in python. Type the command print (“your statement”) and press enter.The statement you wished to print is displayed. This is illustrated below.

If you have used C or Java before you might know to assign a value to a variable ,you will have to define the variable type first and then assign a value to it.But in python you directly say a=2  and python understands the data type by itself

So this shows why python is so easy to use.you don’t have to worry about variable declaration and neither semicolons. In C/C++ , semicolons are must after every statement whereas in python it is not required.

So I hope now you have got an idea of why python is easy.

Next time we will cover the conditional and loop statements in python.

Now that you have python installed in your systems we are all set to start programming in python. So let's begin ! In order to write a… Read more "Let’s code in python !!!"

Are you a gaming freak! Do you love playing android games? And ofcourse you are a fan of pubg! Well then we have another game that can bring some virtual adventure in your life! Yes you guessed it right! It’s fortnite!

Fortnite was first launched as Samsung exclusive,alongside the note 9.It is not available on playstore till now.

Until now you needed an invite to get this game which unfortunately took a lot of time.But Epic has announced on Twitter that it has removed this barrier and now the game can be easily downloaded by scanning a QR code on the site.

Click on this link to know more

https://www.epicgames.com/fortnite/en-US/mobile/android/get-started

You have to allow apps to be downloaded from external sources. No need to panic, just allow it and you are ready to go. This link is of the official site so you need not worry about malwares. However if you are concerned about your security then probably you will have to wait for fortnite launch on Google Play Store.

List of compatible devices is available here:

https://www.epicgames.com/fortnite/en-US/mobile/android/new-device

Know more about fortnite in FAQ section :

https://www.epicgames.com/fortnite/en-US/faq#android

Do comment and let us know whether fortnite can defeat pubg in this battlefield!

Are you a gaming freak! Do you love playing android games? And ofcourse you are a fan of pubg! Well then we have another game that can… Read more "Fortnite on android! Download now!!"

## Getting Started with Python

Let’s get started with the installation of python !

You can check if your system already has python installed by typing the command python in your command prompt or terminal.It should display the version of python installed if python is installed an else it will throw out an error.

In order to open your command prompt , type cmd in your windows search bar aand click on command prompt.

This slideshow requires JavaScript.

If you don’t have python installed in your system then  follow these steps to get it installed.

WINDOWS USERS :

Follow these simple steps to install python

2. Choose the version of python you want.Latest version is what I would recommend.
3. Then just run the file and follow the installation instructions with  default settings.Make sure you check the  “Add Python 3.7 to PATH” checkbox and click on “Install Now”
4. After installation verify by typing python in the command prompt and it should give you the version of python installed.

#### UNIX and LINUX :

Here are the simple steps to install Python on Unix/Linux machine.

• Editing the Modules/Setup file if you want to customize some options.
• run ./configure script
• make
• make install

MAC USERS :