#define light 11

void setup() {
  pinMode(light, OUTPUT);
}

void loop() {
  for (int i = 0; i <= 255; i++) {
    analogWrite(light, i);
    delay(1000);
  }

  for (int j = 255; j >= 0; j--) {
    analogWrite(light, j);
    delay(500);
  }
}