// Define LDR and LED pins
const int LDR_PIN = A0;
const int LED_PIN = 9;

void setup() {
  Serial.begin(9600);
}

void loop() {
  // Read LDR value
  int ldrValue = analogRead(LDR_PIN);

  // Calculate resistance in kOhm
  float resistance = (float)(1023 - ldrValue) * 10 / ldrValue;

  // Calculate lux value

  float lux = pow(10, resistance/4);

  // Turn on LED and measure voltage
  digitalWrite(LED_PIN, HIGH);
  delay(100);
  float voltage = analogRead(LED_PIN) * 5.0 / 1023.0;

  // Turn off LED
  digitalWrite(LED_PIN, LOW);

  // Print measurements to Serial Monitor
  Serial.print("Resistance: ");
  Serial.print(resistance);
  Serial.print(" kOhm, Lux: ");
  Serial.print(lux);
  Serial.print(", LED Voltage: ");
  Serial.print(voltage);
  Serial.println(" V");

  delay(1000);
}