void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(2,OUTPUT);

}

void loop()
 {
  // put your main code here, to run repeatedly:
float sensor=analogRead(A0);
Serial.print("sensor value :");
float sensor1=((sensor*5/1023));
Serial.print(sensor1,"V");
Serial.println("V");

if(sensor1>=3)
{
  digitalWrite(2, HIGH);
}
else
{
  digitalWrite(2, LOW);
}

delay(100);
}