A magnesium atom is not three times heavier than a helium atom!    The atomic number of helium is 2 and relative atomic mass of helium is 4, it has two protons and two neutrons in its nucleus.    Magnesium is in the third row of the periodic table, has an atomic number of 12 … Read more

One of the best know free anti-virus programs that does not urn out to be a limited time trial version that suddenly stops working and leaves you unprotected is AVG.

This program has been around for a long time and gets good reviews in computer magazines.  It comes in two forms - the free version and the … Read more

There are several ways. Perhaps the easiest of all is to simply hit the little button on your keyboard designed to do exactly that! Yes, the one called Print Screen - bet you always wondered why is was there, eh? You now have a copy of the current screen (usually minus the cursor) in the … Read more

Multimedia is where you use some or all of the following types of media - sound, video, animation, images, text. Now text files are rather simple things and take up little space on a hard disk. They are easy to transfer quickly from a device to a computer. Sound files of high quality take up … Read more

PHP stands for PHP: Hypertext Preprocessor. This is called a recursive definition and is a computer geek's idea of a joke. It was developed in 1994 by Rasmus Lerdof as a set of tools to parse and interpret some macros - things like a guest book, a counter and a few other things. This was … Read more

SQL is a programing language designed specifically to add, delete, update information in a relational database. The databse you are using will usually offer several methods of creating a query. a common one is called query by example where you simply select from a graphical display the tables and fields that you wish to be … Read more

Outlook Express is primarily an email client and newgroup reader. It is the default email client supplied with Windows and comes free with Windows. It has all the basic facilities you expect from an email client - multiple identities, creation of folders to categorise stored emails, and automated log-in and log-out. But it is just … Read more

SQL stands for structured query language. It is a programming language designed to work with relational databases, to add, update, delete, or extract data from the database, assuming the database was itself designed to use SQL. Many relational databases add their own little extras to SQL, in an attempt to give them an edge over … Read more

There are several standard types of anomaly in a database. It doesn't need to be a relational database, the same anomalies are present in any database. A properly designed relational database specifically aims to eliminate these anomalies. If the database is not properly normalised, it is susceptible to insertion, update and deletion anomalies. The update … Read more

P block elements are defined as those with which have their valence electrons in their outer most p orbitals. They are the elements on the right hand side of the periodic table, to the top of the table. They are the elements boron, carbon, nitrogen, oxygen, fluorine neon, aluminium, silicon, phosphorus, and sulphur to name … Read more

There are effectively four main branches of science - chemistry, physics, biology and maths. Each at some point will use some of the ideas of the other, although biology ideas don't usually occur very much in maths or physics. Chemistry is concerned with the study of matter, the substances everything is made of. Every substance … Read more

Quite simply, their job is to kill anything they don't recognise as being part of you! Or to put it another way, they attack and kill germs and bacteria that they find in the blood when you have an infection and once they have done that you recover. They don't go hunting for these foreign … Read more

It is the active ingredient on some soaps. First, a little chemistry. Fats and oils, whether of animal or vegetable origin, are all poly esters of glycerol, a tribasic alcohol. Each alcohol group has joined on to it a long chain carboxylic acid to form an ester linkage. Soaps are all made much the same … Read more

The main() function is always, always, user defined. It is the part of a program that makes the other functions, whether they be library functions or user defined ones, run. It is the starting point of the program. Every program in C must have a main() function, or it simply will not run. It cannot … Read more

Normalisation is a process designed to remove redundant data from the records stored in the database and thus to reduce the potential for errors in data input. The data is taken through a series of processes where particular types of redundancy are removed and new tables created. There are strict rules used to ensure that … Read more

Chromatography, like electrophoresis, is a separation technique used by scientists, usually chemists. In chromatography, there is a mobile phase and a stationary phase. The stationary phase is usually a solid, and the mobile phase is usually a liquid or even a gas. As the mobile phase moves over the stationary phase, it takes some of … Read more

A satellite in orbit around a planet is actually falling while moving forward. But it is moving forward just fast enough that its rate of fall matches the curvature of the planet. A satellite is fired into orbit and is pushed hard by the rocket fuel to reach a very high speed, so it starts … Read more

A volt meter measures the potential difference between two points. If its internal resitance was low, a lot of current would flow and this would reduce the potential difference between the points and immediately give you the wrong answer. If the internal resistance is high, and it is usually very very high indeed, then very … Read more

Nice question - well, maybe not. Detecting a smell involves a chemical reaction between a gas you breath into your nose and the smell sensors in your nose. As is normal in chemistry, reactions occur faster at higher temperatures than at lower ones. Farting in the bath expels the gas through hot water, instead of … Read more

An abstract class is a class created solely to be the parent class for several sub-classes and to define some common methods and attributes that the sub-classes will inherit. We will never create an object from an abstract class, it is a starting point from which we will build other classes (which can be instantiated). … Read more