Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
마찰전기는 두 물체가 서로 접촉할 때 발생합니다.Machaljeongi-neun du mulche-ga seoro jeopchokhal ttae balseonghamnida.Triboelectricity occurs when two objects come into contact with each other.