const int sensorPin=0;   // Define Sensor input pin A0
const int ledPin= 13;     // LED pin is 13
const int threshold= 100;  // The value off threshold which will start from it
int PWMLED =6;   // This LED connected  with PWM to change brightness 
                // due to changes  in sensor reading 
void setup()
{
pinMode(ledPin, OUTPUT); //Set ledPin as an OUTPUT
pinMode(PWMLED, OUTPUT); //Set PWMLED as an OUTPUT
Serial.begin(9600);
}
void loop()
{
int val= analogRead(sensorPin); // Define "val" as an integer and save the sensor's
                                  // value there
Serial.println(val); // Display sensor's value on serial monitor

if (val >= threshold) //Compair sensor's value with threshold
{
analogWrite(PWMLED,val); //Transfer sensor's value to the PWMLED
delay(500); //Delay for 0.5s
}
else
analogWrite(PWMLED,0); //if val less than threshold the PWMLED will off
}