Distance calculation using ultrasonic sensor.ino

#include <Wire.h>
#define echoPin 3
#define trigPin 2
long duration;
int distance;
const int buzzer = 8;
const int light = 13;
const int light2 = 12;

void setup(){
  pinMode(trigPin,OUTPUT);
  pinMode(echoPin,OUTPUT);
  Serial.begin(9600); 
  pinMode(buzzer, OUTPUT); 
  pinMode(light, OUTPUT);
  Serial.println("Annamalai University BE CSE 2022 "); // print some text in Serial Monitor
  Serial.println("Distance Measure Program");
}

void loop(){
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2; 
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  digitalWrite(light, LOW);
  digitalWrite(light2, LOW);
  if (distance <= 10)
  {
    Serial.println("Very Close");
    digitalWrite(light, HIGH);
    tone(buzzer, 1000); // Send 1KHz sound signal...
    delay(1000);        // ...for 1 sec
    digitalWrite(light2, LOW);
    tone(buzzer, 500);
    noTone(buzzer);     // Stop sound...
  }
  else if (distance >=11 && distance <=50)
  {
    Serial.println("Near Range");
    digitalWrite(light2, HIGH);
    digitalWrite(light, LOW);
    delay(1000);
  }
  else
  {
    Serial.println("Far Range");
  } 
}