VOLTAGE CURRENT POWER AND ENERGY

1. ACTIVE LEARNING ASSIGNMENTS VOLTAGE CURRENT POWER AND ENERGY Department : Electronics and communication NAME ID NO. JATIN NAIR 13BEECF061 VISHAL HASRAJANI 13BEECG048 DEVASYA DHYANI 13BEECF039 LOHANA DIVYESH 13BEECG047 Guided Teacher : PRIYANKA THAKRE

2. Introduction We are going to discuss some of the important concepts in electrical engineering. Following concepts are discussed here : > Voltage > Current > Power > Energy

3. Voltage All the metals contain a large number of free electrons which move randomly in all the directions, inside the metal piece. If a battery is connected across a metal piece as shown figure, then the free electrons will move in a particular direction. The electrical force or pressure that causes the electron to move in a particular direction is called the electromotive force i.e. EMF. Note that the negatively charged electrons gets attracted towards the positive end of the battery. EMF is also called as voltage or potential difference.

4. Definition:  • Voltage is a representation of the electric potential energy per unit • charge. If a unit of electrical charge were placed in a location, the • voltage indicates the potential energy of it at that point. • In other words, it is a measurement of the energy contained within an • electric field, or an electric circuit, at a given point. • Voltage is a scalar quantity. The SI unit of voltage is the volt, such that • 1 volt = 1 joule/coulomb. • 230V is received for domestic purposes in India. Voltage

6. Definition : • Current is defined as the movement of electrons inside a conducting • material. • In other words, an electric current is a flow of electric charge. • Higher the number flowing electrons, higher is the value of current. • But each electron carries a constant charge on it. Hence we define ‘ • the current as flow of charge per unit time OR the rate of change of • charge with respect to time ’. • Mathematically the charge – current relation can be defined as, Current It is denoted by I and measured in ampere (A).

8. The current due to flow of electrons is called electron current. Thus the electron current flows from the negative end of the battery to the positive end as shown in figure. Current Conventional current : The current is said to be flowing from a positive terminal to a negative terminal. Hence even though the actual electron current flows from the negative terminal, the conventional current is said to flow from the negative to positive terminal, the conventional current is said to flow from the positive end of the battery to the negative end of the battery.

9. Ohms law • Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. • Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship where I is the current through the conductor , V is the potential difference measured across the conductor, and R is the resistance of the conductor. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.

10. Resistance • The electrical resistance of an electrical conductor is the opposition to the passage of an electric current through that conductor • The resistance (R) of an object is defined as the ratio of voltage across it (V) to current (I) through it. The unit of resistance is Ohm (Ω). Resistor

11. Power • Electric power is the rate at which electric energy is transferred by an electric circuit.. • Electric power, like mechanical power, is the rate of doing work, measured in watts, and represented by the letter P. • The SI unit of power is the watt, one joule per second • A commonly used unit is horsepower, • 1 HP = 746 W

13. Energy • A battery transfers stored chemical energy as charged particles called electrons, typically moving through a wire. For example, electrical energy is transferred to the surroundings by the lamp as light energy and thermal (heat) energy. • Lightning is one good example of electrical energy in nature, so powerful that it is not confined to a wire. Thunderclouds build up large amounts of electrical energy. This is called static electricity. They are released during lightning when the clouds strike against each other.

14. Energy • Electric energy is defined as the product of power and time. Energy = Power * Time • The SI unit of energy are Watt second or Joules. E = V * I * t The electricity meters supplied by G.S.E.B are actual energy meters. They measure the energy consumed by the customer in watt hour i.e. Wh, so they are also known as watt hour meters.

15. How to calculate voltage in series ? • Here there are three resistors which are connected in series. • Current remains same everywhere in a series circuit. • I = I1= I2 = I3 • V = V1 + V2 + V3

16. How to calculate voltage in parallel ? • Here there are three resistors which are connected in parallel. • Voltage remains same everywhere in a parallel circuit. • V = V1= V2 = V3 • I = I1 + I2 + I3

17. Division of Voltage in series • Here we have to note that voltage divider rule is calculated for series circuit only because voltage remains constant in parallel connection. • Hence voltage across R1 & R2 is,

18. Division of Current in parallel • Here we have to note that voltage divider rule is calculated for series circuit only because voltage remains constant in parallel connection. • Hence current across R1 & R2 is,

19. KVL (Kirchhoff’s Voltage Law) • The Kirchhoff’s voltage law state that the algebraic sum of voltage around the closed loop in the circuit must be equal to zero. • This is mathematically expressed as : • OR • The sum of the voltage rises is equal to the sum of the voltage drops around the close loop in a circuit.

20. KCL (Kirchhoff’s Current Law) • The Kirchhoff’s current law is also called ‘ point law ’. • It state that the algebraic sum of current directed into any node in a circuit is equal to the sum of currents coming out of the same node. • This is mathematically expressed as : • OR • The algebraic sum of all the current entering or leaving a node must be equal to zero. I1 + I2 = I3 + I4