Introduction

In  this project we will build a Street light project.  Streetlights are lights that are usually mounted on large poles and are used to illuminate roads and  highways. Street lights usually turn on automatically when night begins to fall.

To build this project we need:

1. Unda Xplora Kit
2. Light Dependent Resistor (LDR)
3. 1 single colored LED (pick any color of your choice)
4. 1 220 ohm resistor
5. 1 10Kiloohm resistor

Before we dive into the project, let us look into a little bit of information about the LDR.

A Light Dependent resistor is a type of resistor whose resistance changes depending on the intensity of light.  This is the electrical component that is used in streetlights to determine whether it is dark or during the day in order to turn the lights on or off.

During the day, the intensity of light is higher and thus the LDR has a very high resistance hence the street lights are off and at night the LDR has lower resistance thus the streetlights turn On.

Let’s build the Street Lights Project

Place the LED and a 220ohm resistor on the breadboard. Connect a breadboarding jumper wire between the resistor and the positive pin of the LED.

Connect a jumper wire from digital pin D2 to the resistor placed next to the LED.

Place the LDR and a 10kilo ohm resistor on the breadboard. Place the resistor in such a way that one of its pin is next to one pin of the LDR.

Connect a jumper wire from analog pin A0 to one side of the resistor placed next to the LDR.

Connect a jumper wire from GND to the bottom breadboard negative rail. Connect breadboarding jumper wires from negative rail to the other pin of the LDR and also to the negative pin of the LED.

Once you have completed building the circuit, return to the project window and run the project. Once the project has been uploaded, go to the Play section. Cover the of the LDR using your hand  and observe what happens to both the LED and the Play section window.

What did you observe?

When the LDR is not yet covered by your hand the LED is initially  OFF. This is because the light intensity surrounding the LDR is high and thus this increases the resistance of the LDR.  The high resistance prevents the flow electricity and thus the LED does not receive current that will power it up.

When you cover the LDR with your hand, you realize that LED turns ON. This is because at lower light the resistance of the LDR drops significantly to a lower value which allows the flow of current and thus it is able to power up the LED and it turns On and begins blinking.

This is similar to how street lights tun on and off automatically. During the day, when there is a lot of light, the resistance is high and thus electricity does not get to the streetlights and thus they are off, but when darkness begins to approach, the resistance reduces allowing the flow of electricity and thus it turn the streetlights ON automatically.