Why would it work Wool yarn can be substituted for the human hair in a hygrometer.?

Wool yarn can be substituted for human hair in a hygrometer because it also exhibits hygroscopic properties, meaning it can absorb and release moisture from the air. Like human hair, wool yarn expands and contracts with changes in humidity, allowing it to effectively measure relative humidity levels. Additionally, wool is durable and readily available, making it a practical alternative for constructing hygrometers.