COMPONENTS-

Arduino Board X 1

LDR X 1

LED X 1

5k ohm or above Resistor

What is a LDR?

. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity.

CODE-

int LDRValue = 0;

int led=9;

// result of reading the analog pin

void setup()

{

Serial.begin(9600) // sets serial port for communication

pinMode(led,OUTPUT);

}

void loop()

{

LDRValue = analogRead(LDRpin); // read the value from the LDR Serial.println(LDRValue);

// print the value to the serial port delay(100);

Serial.println(LDRValue);

if(LDRValue<300)

digitalWrite(led,HIGH);

else

digitalWrite(led,LOW);

}