Final answer:
A head crash happens when a hard disk's readwrite head touches the disk surface or particles on it. Modern hard drives primarily use giant magnetoresistance instead of induction to read data stored digitally.
Step-by-step explanation:
A head crash occurs when a readwrite head makes contact with the hard disk's surface or with particles on its surface. Hard drives use a coated, spinning disk where data is stored digitally in the form of 0's and 1's. Historically, read heads worked on the principle of induction, but most modern hard drives utilize giant magnetoresistance (GMR) instead. GMR is a nanotechnology success, enabling the detection of changes in a magnetic field through changes in electrical resistance in thin films of ferromagnetic and nonmagnetic layers. This principle is distinct from older magnetic media, such as audio and video tapes that do use induction, but shares the digital encoding of data with devices like the magnetic stripes on credit cards.
A hard drive crash occurs when a readwrite head makes contact with the hard disk's surface or with particles on its surface. The readwrite head, which hovers just above the spinning disk, reads and writes data onto the disk. When the head touches the surface of the disk, it can cause damage to both the head and the disk, potentially resulting in a loss of data.