## Important Current Electricity Notes

Today we are going to Provide you Current Electricity Notes like Electromotive Force, Resistance, Ohm's Law, Electrical Energy etc.

What is Electromotive Force?
Electromotive Force (E.M.F.) is the force that causes a current of electricity to flow. The Volte is the unit of potential difference and electromotive force.

What is Resistance in Electrical Engineering?
The Opposition to the flow of electron is called electrical Resistance. Resistance may also be defined as "The property of the electric circuit which opposes the flow of current". The Practical Unit of Electrical Resistance is ohm.

What is Ohm's Law?
"For a fixed metal conductor, the temperature and other conditions remaining constant, the current I through it is proportional to the potential difference V between its ends".

in other words, V/I = Constant or V/I = R, where R is the resistance of the conductor between the two points.

Also See - Top Electrical Engineering MCQ on Simple DC Networks

What is Electrical Energy?
Electrical Energy is expressed in terms of KW (kilowatt = 1000W) or MW (megawatt = 1000 KW)

1 kWh = 1 kw * 1 hour = 1000 watt-hours (=1000*60*60 watt-sec.)

What is Linear and Non-linear Resistor?
Linear Resistor - A Linear resistor is one which obeys Ohm's law. A circuit which contains only linear components is called a linear circuit.

Non-linear Resistor - Such elements in which the V/I (volt-ampere) plots are not straight lines but curves are called non-linear resistors or non-linear elements.

What is the Limitation of Ohm's Law?
Ohm's law does not apply under the following conditions:
1. Electrolytes where enormous gases are produced on either electrode.
2. Non-linear resistors like vacuum radio valves, semi-conductors, gas-filled tubes etc.
3. Arc lamps.
4. Metals which get heated up due to the flow of current through.
5. Appliances like metal rectifiers, crystal detectors, etc. in which operation depends on the direction of the current.

Classification of Resistors
The resistors 'are classified as follows:

1. Fixed resistors - The fixed resistor is the simplest type of resistor. Fixed means that the unit is so constructed that its resistance value is constant and unchangeable. These are made of a carbon composition and have a cover of black or brown hard plastics.

2. Tapped resistors - A tapped resistor is a resistor which has a tap, or connection, somewhere along the resistance material. These resistors are usually wire wound type. If they have more than one tap, they will have a separate terminal for each.

Also See - Top 24 Basic Electrical Engineering Questions with Answers

3. Variable resistors - A variable resistor has a movable contact that is used to adjust or select the resistance value between two or more terminals. A variable resistor is commonly called a control.

4. Special resistors - The most common type of special resistors is the fusible type. A fusible resistor has a definite resistance value and it protects the circuit much like a fuse. Another special resistor is the temperature compensating unit. Such resistors are used to provide special control of the circuit that must be extremely stable in their operation.

We hope that this post "Important Current Electricity Notes for Students" will help you in your preparation. if you have any suggestion and request, you can tell us through comment here.

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