#define ldrPin 2
const float gama = 0.7;
const float rl10 = 50;

void setup() {
  Serial.begin(115200);
}

void loop() {
  delay(10);
  int nilaiLDR = analogRead(ldrPin);
  nilaiLDR = map(nilaiLDR, 4095, 0, 1024, 0);
  float voltase = nilaiLDR / 1024.*5;
  float resistansi = 2000 * voltase / (1-voltase/5);
  float kecerahan = pow(rl10*1e3*pow(10,gama)/resistansi,(1/gama));
  Serial.print("Kecerahan = ");
  Serial.println(kecerahan);
}