int sensorPin = A0;    // select the input pin for the potentiometer
int ledPin = 7;      // select the pin for the LED
int sensorValue = 0;  // variable to store the value coming from the sensor

void setup() {
  // declare the ledPin as an OUTPUT:
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // read the value from the sensor:
  sensorValue = analogRead(sensorPin);
  // turn the ledPin on

 if ( sensorValue == 1023)
 {
  digitalWrite(ledPin, HIGH);
 }
  else if (sensorValue == 0){

  // turn the ledPin off:
  digitalWrite(ledPin, LOW);
  }

}