The MOSFET has a resistance. When current flows from the MOSFET's drain to its source, there will be a voltage drop. Multiply that current and voltage to get the power loss. That lost power becomes heat.
The MOSFET must get rid of that heat, usually by passing it into the air.
Smaller MOSFETs warm up and heat the nearby air. Some MOSFETs must be on a circuit board, which has a larger area to heat more air. The highest-power MOSFETs must be on a heatsink. The heatsink is a large piece of metal with fins to transfer the heat to the air over a large area. They may also need a fan to push lots of air over the heatsink.
There are lots of different MOSFETs available. When choosing a MOSFET, once you have decided among the 4 main types, there are lots of other things to think about. Differences between MOSFETs include:
There are many different ways to make MOSFETs on the semiconductor. The simplest method is shown in the diagram to the right of this text. The blue part represents P-type silicon, while the red part represents N-type silicon. The intersection of the two types makes a diode. In silicon semiconductor, there is a quirk called the "Depletion Region". In doped silicon, with one part being doped N-Type, and one part being doped P-Type, a depletion region will naturally form on the intersection between the two. This is because of their acceptors and donors. P-type silicon has acceptors, also known as holes, which attract electrons towards them. The N-Type silicon has donors, or electrons, which are attracted to holes. In the border between the two, the electrons from the N-Type fill the holes in the P-type. This results in the acceptor, or P-type atoms becoming negatively charged, and since negative charges attract positive charges, acceptors, or holes, will flow towards the "junction". On the N-Type side, there is a positive charge, which results in the donors, or electrons, flowing towards the "junction." When they get there, they will be repelled by the negative charge on the other side of the junction, since alike charges repel. The same will happen on the P-Type side, the donors, or holes will be repelled by the positive area in the N type side. No electricity can flow between the two, since no electrons can move to the other side.
MOSFETs use this to their advantage. The "Body" of the MOSFET is powered negatively, which widens the depletion region, since the holes are filled with the new electrons, so the opposite force to the electrons on the N side becomes much larger. The "Source" of the MOSFET is powered negatively, which shrinks the depletion zone in the N type entirely, since there are enough electrons to fulfill the positive depletion zone. The "Drain" has a positive power. When the "Gate" is supplied with positive power, it will make a small electromagnetic field, which will remove the depletion zone directly below the gate, since there will be a "spray" of holes, which will make something called an "N-Channel". The N-Channel is a temporary region of the P-Type silicon area where there is no depletion zone. The positive electric field will neutralize all of the spare electrons that make up the depletion zone. The electrons in the source area will then have a clear way to move to the "Drain", which would make electricity flow from source to drain.
First Punic War
The First Punic War started in 264 BC. It lasted for 23 years, ending in 241 BC. It was the first of three wars fought between ancient Carthage and the Roman Republic. They were rivals for trade and influence in the Mediterranean. For more than 20 years the two powers struggled for supremacy. Key areas were the island of Sicily and its surrounding waters, and also North Africa. Rome eventually won control of Sicily.
With the help of her own allies and rebels among the indigenous African allies of Carthage, Rome won the First Punic War after 23 years. In the end it became the dominant naval power of the Mediterranean. To get terms for peace, the Carthaginians had to pay a large amount of money (in silver), and give up a number of islands in the Mediterranean. They kept Sardinia and Corsica.
Scott Westerfeld
Scott Westerfeld is an American author of science fiction and young adult literature. One of his most famous book series was "Uglies".
Partial differential equation
Partial Differential equations (abbreviated as PDEs) are a kind of mathematical equation. They are related to partial derivatives, in that obtaining an antiderivative of a partial derivative involves integration of partial differential equations.
Since PDEs have appeared in mathematics and physics, many scientists have studied methods to solve them. But unfortunately, no one could establish methods to solve any kind of PDE. Therefore, numerical methods for PDEs (such as the finite element method) are widely studied since the appearance of computers.
Trade paperback (comics)
Unlike graphic novels, the material in a trade paperback is reprinted from comic magazines that were released in the standard 32-page format. Unlike comic books, which only tell one small part of a story, trade paperbacks usually collect a complete story, story arc, or a large part of a story. They usually reprint the material from 4 to 12 comic books, depending on the size of the trade and the story being collected.
Some famous examples of trade paperbacks:
Mathematical induction
Mathematical induction is a special way of proving a mathematical truth. It can be used to prove that something is true for all the natural numbers (or all positive numbers from a point onwards). The idea is that if:
then
In the careful language of mathematics, a proof by induction often proceeds as follows:
Because it is true for 1, then it is true for 1+1 (=2, by the induction step), then it is true for 2+1 (=3), then it is true for 3+1 (=4), and so on.
An example of proof by induction is the following:
Prove that for all natural numbers "n":
Proof:
First, the statement can be written as:
By induction on "n",
First, for "n"=1:
so this is true.
Next, assume that for some "n"="n" the statement is true. That is,:
Then for "n"="n"+1:
can be rewritten as
Since formula_12
Hence the proof is complete by induction.
Mathematical induction is often stated with the starting value 0 (rather than 1). In fact, it will work just as well with a variety of starting values. Here is an example when the starting value is 3: "The sum of the interior angles of a formula_1-sided polygon is formula_15 degrees."
The initial starting value is 3, and the interior angles of a triangle is formula_16 degrees.
Assume that the interior angles of a formula_1-sided polygon is formula_15 degrees. Add on a triangle which makes the figure a formula_5-sided polygon, and that increases the count of the angles by 180 degrees formula_20 degrees. Since both the base case and the inductive case are handled, the proof is now complete.
There are a great many mathematical objects for which proofs by mathematical induction works. The technical term is a "well-ordered set".
The same idea can work to "define" a set of objects, as well as to prove statements about that set of objects.
For example, we can define formula_1th degree cousin as follows:
There is a set of axioms for the arithmetic of the natural numbers which is based on mathematical induction. This is called "Peano's Axioms". The undefined symbols are | and =.
The axioms are
One can then define the operations of addition and multiplication and so on by mathematical induction. For example:
Kader Abdolah
Kader Abdolah (born 1954) is a Dutch author who was born in Iran.
Kader Abdolah was born "Hossein Sadjadi Ghaemmaghami Farahani" () in Arak, Iran. Since 1988 he has been living in the Netherlands.