const int trigPin=9;
const int echoPin=10;

const int relayPin=8;

long duration;
int distance;

void setup() {
Serial.begin(9600);
pinMode(trigPin, OUTPUT); // put your setup code here, to run once;
pinMode(echoPin, INPUT);
pinMode(relayPin, OUTPUT);

digitalWrite(relayPin, LOW);
}

void loop() {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10); // put your main code here, to run repeatedly;
digitalWrite(trigPin, LOW);

duration=pulseIn(echoPin, HIGH);
distance=duration*0.034/2;

Serial.print("Distance:");
Serial.print(distance);
Serial.println("cm");

if (distance<10) {digitalWrite(relayPin, HIGH);}
else {digitalWrite(relayPin, LOW);}

delay(100);
}