int Led = 13 ; // define LED Interface
int SENSOR = 10 ; // define the Hall magnetic sensor interface 
int val ; // define numeric variables val
void setup ()
{
pinMode (Led, OUTPUT) ;  // define LED as output interface
pinMode (SENSOR, INPUT) ; // define the Hall magnetic sensor line  as input
}
void loop ()
 
{
val = digitalRead (SENSOR) ; // read sensor line
if (val == LOW) // when the Hall sensor detects a magnetic field, ArduinoLED lights up
{
digitalWrite (Led, HIGH);
}
{
digitalWrite (Led, LOW);
}
}

