Q.No.13 - WAP to interface LED and Buzzer with Arduino board keeping the condition that whenever LED glows, there is a Buzzer ringing and when LED is off then Buzzer is also put on off.

Sol.- Buzzer on when LED ON and vice versa. 

            int led=2;
            int buzzer=7;
            void setup()
            {
              pinMode(led, OUTPUT);
              pinMode(buzzer, OUTPUT);
            }
            
            void loop()
            {
              digitalWrite(led, HIGH);
              digitalWrite(buzzer, HIGH);
              delay(1000); // Wait for 1000 millisecond(s)
              digitalWrite(led, LOW);
              digitalWrite(buzzer, LOW);
              delay(1000); // Wait for 1000 millisecond(s)
            }

OUTPUT: