Final answer:
True, magnetic disks have been the most widely used secondary storage medium, using magnetic encoding of digital information. Advancements such as giant magnetoresistance have improved data reading capabilities. However, new technologies like SSDs and cloud storage are becoming more popular.
Step-by-step explanation:
The statement that magnetic disks are the most widely used secondary storage medium is generally true. These disks, including traditional hard drives, operate by magnetically encoding digital information—a series of 0s and 1s—onto a spinning disk. Despite advancements in technology, magnetic disk drives remain prevalent due to their balance of cost, capacity, and speed. Technologies such as giant magnetoresistance (GMR) have made it possible to read the stored data. GMR utilizes the change of electrical resistance induced by magnetic fields in ferromagnetic layers, representing a significant application of nanotechnology. Still, there is a clear trend with newer technologies like solid-state drives (SSDs) and cloud storage gaining popularity due to faster speeds and greater durability.
Additionally, it is true that credit cards should not be placed near permanent magnets, as this can demagnetize the magnetic strip, affecting its functionality. When it comes to multimedia, CDs and DVDs were common for their larger storage capacity compared to magnetic tapes. They store information digitally, using lasers to read data from tiny pits on their surface. However, these optical media have been largely superseded by streaming services and other digital storage solutions.