arduino ultrasonic sensor relay

// Use the HC-SR04 to detect movement after 13 CM to turn on a light for 15 seconds

#define trigPin 6                       //Define the HC-SE04 triger on pin 6 on the arduino
#define echoPin 5                       //Define the HC-SE04 echo on pin 5 on the arduino
#define bulb 9                          //Define the relay signal on pin 9 on the arduino

void setup()
  {
    Serial.begin (9600);                //Start the serial monitor
    pinMode(trigPin, OUTPUT);           //set the trigpin to output
    pinMode(echoPin, INPUT);            //set the echopin to input 
    pinMode (bulb, OUTPUT);             //set the bulb on pin 9 to output
  }
  
void loop()
  {
    int duration, distance;             //Define two intregers duration and distance to be used to save data
    digitalWrite(trigPin, HIGH);        //write a digital high to the trigpin to send out the pulse
    delayMicroseconds(500);             //wait half a millisecond
    digitalWrite(trigPin, LOW);         //turn off the trigpin
    duration = pulseIn(echoPin, HIGH);  //measure the time using pulsein when the echo receives a signal set it to high
    distance = (duration/2) / 29.1;     //distance is the duration divided by 2 becasue the signal traveled from the trigpin then back to the echo pin, then devide by 29.1 to convert to centimeters
    
    if (distance < 7)                  //if the distance is less than 13 CM
    {        
     ac();                           //execute the Light subroutine below
    }
    else                   //if the distance is less than 13 CM
    {        
     kapat();                           //execute the Light subroutine below
    }
//    else 
//    Serial.print(distance);             //Dispaly the distance on the serial monitor 
//    Serial.println(" CM");              //in centimeters
//    delay(500);                         //delay half a second
  }
  
void ac()                            //Start the Light subroutine
  {
  digitalWrite(bulb, HIGH);             //turn on the light
  delay (500);                        //wait 15 seconds
//  digitalWrite(bulb, LOW);              //turn off the light
  }
  void kapat()                            //Start the Light subroutine
  {
//  digitalWrite(bulb, HIGH);             //turn on the light
  delay (500);                        //wait 15 seconds
  digitalWrite(bulb, LOW);              //turn off the light
  }