Getting started with electric circuits

Now that we have learnt all about electronic components, their types and applications. In this tutorial we'ii get to the business of combining one or more components to form a complete circuit, let's get ready! 

Electric circuit is the path through which electric current flows between two or more components.  An electric circuit is formed when components like resistors, inductors, capacitors, switches and integrated circuits are wired together. 

Electronic components are use to manipulate current, before we move forward  let's learn about few analogy used in circuits. ln electronics we use some common words often like current, voltage and resistance. Consider a battery supplying current to a circuit, we specify the force which pulls out electrons as voltage and the rate of flow of the electrons as current and also, the reduction or opposition to the rate of flow of current as resistance. 

In electrical/electronics engineering these three analogies are used especially in circuits, so we need a better understanding on them. 

Voltage.

it is the measure of force which pulls out electrons from sources e.g batteries. Current: it is rate of flow of electrons from a power source to a circuit. 

 Resistance.

it the opposition to the flow of current offered by a resistive material. Gorge ohm was a bravarian scientist who studied electricity and their characteristics in conductors like metals and electrolytes. Goerge Ohms proposed his ohms law of how current interacts with different conductive medium and the relationship between resistance, voltage and current. The unit of resistance(ohms) was named after him. 

Explaining voltage, current, resistance, power and energy with water analogy.

1. Voltage. 

For example, a tank or reservoir filed with water and placed above the ground some distance, when a pipe is connected from the tank downwards and made to deliver water, it gushes out with great force depending on it height above the ground. So the force that makes the water gush out is known as voltage, in electricity voltage is measured in volts e.g 12v, 220v etc. .

2. Current. 

The amount of water delivered from the tank(battery) and it depends on pressure (voltage).  A bigger pressure will deliver a large amount of water(current) than a little one. The rate at which current flows in a circuit is measured in Ampere e.g 20A, 0.45A etc. Sometimes the amount of current produced depends on the voltage but, not in all cases. We can have a power source of 12v and still supply a current of 18A. It all depends on the source of electricity and some other factors.   

3. Resistance. 

When a pipe that delivers water from the tank is made big, the water delivered is much because of the little resistance offered by the pipe to the flow of water. But when it is of small size, it delivers little because of large resistance to the flow of water in the pipe. In circuits, resistance is the opposition to the flow of current. So when electric current passes through a conductor in a circuit, the resistance depends on the nature of the material and the cross sectional area. Resistance is measured in ohms.     

 4. Power.

It is measured in watts, it's the amount or rate of energy absorbed by a circuit. The power of a circuit can be different from another because one might consume or require much power than another one. For example an heating element will consume more power than a light bulb, thus the element has more wattage than the bulb.  Power is usually calculated by multiplying the absorbed current by voltage, P= IV. 

5. Energy. 

It is the work done or energy produced by the flow of electrons in a circuit. For example, electrons produce energy when it makes an electric motor to work, and also energy is produced when a light bulb produce light when it is connected to power supply. Energy is measured in joules (J). 

 

How to build a simple circuit.

A simple circuit do consist of a switch, resistors,  LEDs and many other components.  

Materials:

1. LED. 

2. Wire 

3. 9v battery. 

4. 470 ohms resistor. 

In this activity we shall learn how to connect an LED to a battery and make it light. 

 Steps.

Connect the positive terminal of the LED in series with the positive terminal of the battery and the 470 ohms resistor in series between the negative terminal of the  battery and the LED as shown in the circuit diagram below.

Connect the battery to allow current to flow from the battery to the LED. The LED should glow if connected properly. The 470 ohm resistor reduces excess voltage to avoid burning up the LED, if the LED is connected directly to a battery it will burn up because LEDs can only operate between 1.5v to 2v with a maximum current of 0.5A.