911. How long will a magnetic tape stay magnetized? Won't it lose its magnetization very fast, like we saw with the iron nails?
At room temperature, a magnetic tape will remain magnetized for years and years. It is made of much harder magnetic materials than the nails are made of and it is much harder to demagnetize than the nails. In effect, it is covered with tiny permanent magnets and you have seen permanent magnets that remain magnetic for decades or centuries.