Working priciple

Working Principle

Normally, an unused analog pin is called a floating pin.

A floating pin can pick up tiny electrical signals from:

• Human body
• Nearby wires
• Electronic devices
• Static electricity in the environment

When a person touches the A0 pin, the analog value changes.

The Arduino reads this value using:

analogRead(A0);

If the value becomes greater than 500:

• LED turns ON

If the value is less than 500:

• LED turns OFF

Output

• Touch A0 pin → LED glows.
• Remove finger → LED may turn OFF.
• Serial Monitor shows changing values.
• RX/TX LEDs blink because data is sent continuously to the computer.