Diode or pn junction:Definition, explanation, construction

Definition:

"Diode is an electrical component which allow the current to flow in one direction."

Explanation:

Diode is use to flow the current only in one direction and to block the current, if it flows in other direction. This property of blocking current in one direction and allowing it in only one direction is due to its construction which is explain below. It does not change the current, it just block the current to flow in other direction in a circuit. It is also use to convert AC source into DC source.

By blocking the negative interval and allowing only positive interval and by using some filter, decreases the fluctuation.

Construction:-

The diode is made up by the junction of two semiconductor of same material, lets suppose Silicon (Germanium could also be used). One semiconductor is doped with p type material which is boron and other semiconductor with n type material which is phosphorus. This junction is known as P-N junction. 

                                 

In P there is holes which is majority charge and in N there is electrons which is majority charge.

When we make junction of these (p-type and n-type) then holes which are majority charges in P, moves towards the N, and combine with the electrons, and majority charges in 

N which are electrons moves towards the P junction and combine with the holes.

 During this process there form a junction which is known as PN junction. Which consists both holes and electrons. And no more transfer of electrons and holes occurs(because of this junction wall.).

Working:

In electric Circuit, we take symbol for diode is, 

There are bias (applying any source) condition for semiconductor diode. Forward bias and Reverse bias. Diode works only in forward bias. In reverse bias, it blocks the flow of current in circuit or in other words. It becomes open circuit. which is its main property to allow current in only in one direction.

how to forward bias the diode?

We could do it by connecting positive terminal of voltage source from the anode and negative terminal with the cathode. And for reverse bias its vice versa.

How it allows current to flow in forward bias?

It allows current to flow in forward bias, because we connect positive terminal of voltage source with anode and it attracts electron from the N type. So electrons start to flow towards the anode terminal. And there is junction wall between diode, so to overcome there needs voltage of 0.3 or 0.7 . so could say that it is diode starting voltage.

How it blocks current in reverse bias? 

It blocks current in reverse bias, because the positive terminal of voltage source is connected with the cathode so it attracts electron towards cathode terminal so because of it, negative electrons from P type and positive holes from N type goes into junction and increases it. so junction widens and blocks the transfer.

What is Charge, current, voltage? Definition explanation

Charge

Definition:

“Charge or Electrical charge is the property of, unit of a matter”

Explanation:

Charge does not physically exist; this is only a theoretical word. Yes, we use the word charge physically in many topics, just to describe the topic by taking a simple or basic thing (charge). Charge tells that how the matter will react with the other matter or in a magnetic field or in a electric field.

A matter is named as charge, only when there is a difference in number of electrons and number of protons in atom of that matter. If there are more electrons than proton in atom then it is negative charge and if there are more protons than electrons then it is positive charge. Hence this is two types of charge negative and positive charge.

Unit:-

The unit of charge is Coulomb and represented by q. 

Current

Definition:-

“Current is the rate of flow of electric charges.”

Explanation:-

Current is the flow of electric charges which is free electrons. Current flows in a circuit when there is pressure or some force applied to the charges in a circuit. Current flows from negative end to towards positive end. Rate of flow means, how much charges will flow in some fix time. There are two types of current. AC and DC.

AC means alternating current. The current which changes its direction of flow after half interval is known as alternating current.

DC means direct current. The current which flow in only one direction is known as DC current.

Each type of current has its own application.

Unit:-

Unit of current is A Ampere.

“When one coulomb charge will flow in one second through some point, then current will be one ampere.”

 Voltage

Definition:-

“Voltage is a force or pressure which causes the charges to flow through circuit.”

Explanation:

As we discuss in explanation section of current that , current flows through the circuit when some force or pressure applied to the charges in circuit. That force and pressure is Voltage. It is also known as potential difference. In some words, Voltage is the power of current. Means with how much power the current is flowing. The more the voltages the more the rate of flow of current in a circuit.

Unit:

Unit of voltage is V volt.

Electric Potential: definition, explanation, example.

Definition:

"Electric potential is the amount of word done in moving a point test charge from its original position(reference position) to some specific point or position, while moving the charge in direction opposite to direction of field in which charge is present."

Explanation:-

The definition above seem to be difficult to understand the electric potential but I will explain it briefly.
Consider their is a positive point charge A, which have its own electric field around it. And there is another positive test charge B which has no electric field.

 When we will move the test charge B towards the electric field of point charge A then test charge B will move away from the point charge A. This is natural that charge always move from high potential to low potential.

low potential is the area where the charge feels less force while high potential is the area where the force is high.

So to move charge, against its natural movements. we have to provide electric potential or force or to do work. To move test charge B towards the charge A we have to apply some potential which is electric potential, to move the charge from low potential to high potential. So charge B will gain potential energy while moving towards high potential from low potential.

Electric potential is the basic studies of charges behavior with each other. So if you feel there is some type of confusion feel free to comment. The post will be update!

Ampere's law: explanation, definition, formula

Definition:-

"Ampere's Law states that magnetic field around a conductor in which electric current is flowing, is directly proportional to the amount of electric current flowing through conductor."

Explanation:

Ampere's law provide us method or formula to calculate magnetic field, produced by electric current.
Just like electric field is directly proportional to the amount of charge, the magnetic field is directly proportional to the amount of electric current from which it is producing.

Formula:-

The most difficult in ampere's law is to derive its equation or make the formula for calculating the magnetic field around a long conducting wire.
So let's start this,
Consider we have long straight conducting wire, when electric current flows through it, the magnetic fields produces around the wire in concentric circle. As shown in below pic.

Every circle is for some specific part of wire and as we move forward in wire, the distance between these circles increases, that mean magnetic field is decreasing. Direction of magnetic field can be found by Fleming's right hand rule.(with direction of current giving)
Now to make the formula, consider there all the parts of wire( which have there magnetic field circuit) having length L and there magnetic field around these parts or elements is B for (every part).

So the equation will become,

And after removing proportionality,

where 𝝁 is the premiability of material or conductor.
B is the magnetic field and delta L is the sum of all length parts and I is the current flowing through the conductor,
sigma shows that the sum of all the length elements or parts with their magnetic field.
Where delta L could be replace by 2πr for particular(single part) length element.
So Then magnetic filed would become,