Overview
When beginning to explore the world of electricity and electronics, it is vital to start by understanding the basics of voltage, current, and resistance. These are the three basic building blocks required to manipulate and utilize electricity. At first, these concepts can be difficult to understand because we cannot "see" them. One cannot see with the naked eye the energy flowing through a wire or the voltage of a battery sitting on a table. Even the lightning in the sky, while visible, is not truly the energy exchange happening from the clouds to the earth, but a reaction in the air to the energy passing through it. In order to detect this energy transfer, we must use measurement tools such as multimeters, spectrum analyzers, and oscilloscopes to visualize what is happening with the charge in a system. Fear not, however, this tutorial will give you the basic understanding of voltage, current, and resistance and how the three relate to each other.Sections
In this lesson we discuss about:
- History of Electricity.
- Types of Electricity.
- Statics Electricity.
- Current.
- Type of Current
- Units
- Ampere
- Volts
- watts
- capacitance
- Components
- Resistors
- Capacitor
- Diodes
- LED's
- LDR
- Transistors
- Multimeter
- Hands-on projects
- How to make Resistors
- How to make capacitor
- How to make Electromagnet
- How to make Static electric generator
- Design your own galvanometer
- Make electricity by lemons
- How to make Hydrogen Fuel Cell
- Build Your Own Battery Cell from Activated Carbon
- How to Make a Simple Electric Generator
- Homemade solar cell construction (Urdu)
- AC Generator, Simple DIY project with Step by Step instructions
- How to make a wind turbine for School Science Project
- Make a Simple DC motor with easy and Step by Step instructions
- Make simple linear motor
- Build Simple Electrostatic Franklin's Motor
- Make Simple DC Generator
- How to make a Wireless electricity transfer project
- How to Make AC generator "Permanent magnet alternator" from old Hard disk drive magnets
History of Electricity
Watch video # 1
Source: Shock and Awe: The Story of Electricity Professor Jim Al-Khalili tells the electrifying story of our quest to master nature's most mysterious force: electricity. Until fairly recently, electricity was seen as a magical power, but it is now the lifeblood of the modern world and underpins every aspect of our technological advancements.
Watch video # 2 History of Electricity Urdu by Takhti Online
Type of Electricity
2. Type of Electricity
There are two main types of electricity, Static Electricity, generated by rubbing two or more objects causing to build up friction, Current Electricity, generated by the flow of electrical charge through a conductor across an electrical field.
A. Static Electricity
Static means not moving. Static electricity is an electrical charge that doesn't move.
- How is static electricity generated
Static electricity is a surface phenomenon and is generated when two or more surfaces come into contact with one another and are separated again. This causes a sort of splitting, or a transfer of negative electrons from one atom to the other. The level of charge, (the field strength) is dependent on a number of factors: the material and its physical and electrical properties, temperature, humidity, pressure and speed of separation. The greater the pressure or the speed of separation, the greater the charge
Hands-on Project related to Static Electricity
- How to make Static electric generator
- Make your own Equipment for static electricity
- DIY Van De Graaff Generator Using PVC pipe
- Static Electricity Science Fair Project
- How to make an Electroscope
- How to make capacitor
- Build Simple Electrostatic Franklin's Motor
B. Current
Definition: Electric current is defined as the rate of flow of negative charges of the conductor. In other words, the continuous flow of electrons in an electric circuit is called an electric current.
Unit: A "Ampere"
There are two types of electric current: direct current (DC) and alternating current (AC). The electrons in direct current flow in one direction. The current produced by a battery is direct current. The electrons in alternating current flow in one direction, then in the opposite direction.
Projects
Material Required:
- Copper wire 25 and 28 gauge
- Multimeter
- Aluminium foil
- Zinc and copper strips
- paper
- salt water
- conducting wire
- LEDs
- motors
- Magnets
- PVC pips
- crocodile clips
Project #1 How To make galvanometer
See Also: Design your own galvanometer
Project # 2 How To make Simple Generator
See Also: How to Make a Simple Electric Generator (Diagrams and working principle)
Project # 3 How To make Simple Generator
Project # 4 How to build Electric Generator. (Recommend for Class7+)
Assignment # 1 Disassembling and assembling of DC motor
In this lesson, the student will have to open the DC motor and then close the same way and draw the parts of this motor on his own worksheet.
Download Worksheet
Curriculum link:
This lesson link with 10th class physics topic The Motor
Project # 5 Make DC Motor (Optional)
Project # 6 Fruit Battery
Teacher Resources
We define voltage as the amount of potential energy between two points on a circuit. One point has more charge than another. This difference in charge between the two points is called voltage. It is measured in volts, which, technically, is the potential energy difference between two points that will impart one joule of energy per coulomb of charge that passes through it (don't panic if this makes no sense, all will be explained). The unit "volt" is named after the Italian physicist Alessandro Volta who invented what is considered the first chemical battery. Voltage is represented in equations and schematics by the letter "V".
When describing voltage, current, and resistance, a common analogy is a water tank. In this analogy, charge is represented by the water amount, voltage is represented by the water pressure, and current is represented by the water flow. So for this analogy, remember:
- Water = Charge
- Pressure = Voltage
- Flow = Current
Consider a water tank at a certain height above the ground. At the bottom of this tank there is a hose.
The pressure at the end of the hose can represent voltage. The water in the tank represents charge. The more water in the tank, the higher the charge, the more pressure is measured at the end of the hose.
We can think of this tank as a battery, a place where we store a certain amount of energy and then release it. If we drain our tank a certain amount, the pressure created at the end of the hose goes down. We can think of this as decreasing voltage, like when a flashlight gets dimmer as the batteries run down. There is also a decrease in the amount of water that will flow through the hose. Less pressure means less water is flowing, which brings us to current.
Current
We can think of the amount of water flowing through the hose from the tank as current. The higher the pressure, the higher the flow, and vice-versa. With water, we would measure the volume of the water flowing through the hose over a certain period of time. With electricity, we measure the amount of charge flowing through the circuit over a period of time. Current is measured in Amperes (usually just referred to as "Amps"). An ampere is defined as 6.241*10^18 electrons (1 Coulomb) per second passing through a point in a circuit. Amps are represented in equations by the letter "I".
Let's say now that we have two tanks, each with a hose coming from the bottom. Each tank has the exact same amount of water, but the hose on one tank is narrower than the hose on the other.
We measure the same amount of pressure at the end of either hose, but when the water begins to flow, the flow rate of the water in the tank with the narrower hose will be less than the flow rate of the water in the tank with the wider hose. In electrical terms, the current through the narrower hose is less than the current through the wider hose. If we want the flow to be the same through both hoses, we have to increase the amount of water (charge) in the tank with the narrower hose.
This increases the pressure (voltage) at the end of the narrower hose, pushing more water through the tank. This is analogous to an increase in voltage that causes an increase in current.
Now we're starting to see the relationship between voltage and current. But there is a third factor to be considered here: the width of the hose. In this analogy, the width of the hose is the resistance. This means we need to add another term to our model:
- Water = Charge (measured in Coulombs)
- Pressure = Voltage (measured in Volts)
- Flow = Current (measured in Amperes, or "Amps" for short)
- Hose Width = Resistance
Resistance
Consider again our two water tanks, one with a narrow pipe and one with a wide pipe.
It stands to reason that we can't fit as much volume through a narrow pipe than a wider one at the same pressure. This is resistance. The narrow pipe "resists" the flow of water through it even though the water is at the same pressure as the tank with the wider pipe.
In electrical terms, this is represented by two circuits with equal voltages and different resistances. The circuit with the higher resistance will allow less charge to flow, meaning the circuit with higher resistance has less current flowing through it.
This brings us back to Georg Ohm. Ohm defines the unit of resistance of "1 Ohm" as the resistance between two points in a conductor where the application of 1 volt will push 1 ampere, or 6.241×10^18 electrons. This value is usually represented in schematics with the greek letter "Ω", which is called omega, and pronounced "ohm".
Source: learn.sparkfun.com
