Kirchoff’s Laws

Kirchoff’s Voltage Law

Step 1:- Select one of the loops in the circuit

Step 2:- Choose a direction out of clockwise and anti-clockwise for the loop chosen

Step 3:-Identify the direction of the current component of each branch of the loop

chosen.

Kirchoff’s Current Law

Step1: Select a node.

Step 2:-Identify the currents entering to the node and currents leaving from the node.

Here is the example for Kirchoff's law problem. 

Part1

Part2

Resistors

 Resistors

Resistors, (R) are the most fundamental and commonly used of all the electronic components. There are many different Types of Resistor available for the electronics constructor to choose from, from very small surface mount chip resistors up to large wire-wound power resistors.

The principal job of a resistor within an electrical or electronic circuit is to “resist” or to set the flow of electrons (current) through them by using the type of conductive material from which they are composed. Resistors can also be connected together in two different ways. Those are series and parallel combinations to form resistor networks which can act as voltage droppers or current limiters within a circuit.

Types of resistors

There are thousands of different types of Resistor and are produced in a variety of forms because their particular characteristics and accuracy suit certain areas of application, such as High Stability, High Voltage, High Current etc, or are used as general purpose resistors where their characteristics are less of a problem.

Types of resistors

•  Carbon resistors

The Carbon Resistor is a low to medium type power resistor which has a low inductance making them ideal for high frequency applications but they can also suffer from noise and stability when hot. Carbon resistors are generally prefixed with a “CR” notation (eg,CR10kΩ ) and are available in E6 ( ± 20% tolerance (accuracy) ), E12 ( ± 10% tolerance) and E24 ( ± 5% tolerance) packages with power ratings from 0.125 or 1/4 of a Watt up to 5 Watts.

• Film type resistors

The generic term “Film Resistor” consist of Metal Film, Carbon Film and Metal Oxide Film resistor types, which are generally made by depositing pure metals, such as nickel, or an oxide film, such as tin-oxide, onto an insulating ceramic rod or substrate.

• Wire wound type resistors

Another type of resistor, called a Wire wound Resistor, is made by winding a thin metal alloy wire (Nichrome) or similar wire onto an insulating ceramic former in the form of a spiral helix similar to the film resistor above.

AC and DC current

Electricity flows in two different ways: either in an alternating current (AC) or in a direct current (DC). Current is nothing but the movement of electrons through a conductor, like a wire. Actually electrons flows in opposite flow of direction to the current.

The difference between AC and DC lies in the direction in which the electrons flow. In DC, the electrons flow steadily in a single direction. In AC electrons keep switching directions, sometimes going "forward" and then going "backward."The best way to transmit electricity over large distances is used alternating current .

Differences  of AC and DC current

 

Electronics

Everyone today is exposed to electronic devices. The computer revolution is a most famous example.  A study of electronics starts with electricity mainly focusing to AC and DC current and some of the basic electronics components.  And also this includes Ohm's law and other basic principles of electricity .  By referring various books on electronics  you can gain more knowledge of these basic electronics concepts. Let's move on Ohm's law and types of current.

Ohm's law :

Ohm's Law deals with the relationship between voltage(V) and current(I) in an ideal conductor. This relationship states that:
The potential difference (voltage-V) across an ideal conductor is proportional to the current (I)through it.The constant of proportionality is called the "resistance" and it denote by R.
through this definition Ohm's law can be:
    V = I R
where V is the potential difference between two points which include a resistance R. I is the current flowing through the resistance.