A hardware engineer is analyzing the playback mechanism of an archival storage format. The drive uses a low-power laser diode and a photodiode sensor to read data along a continuous spiral track on a spinning reflective disk.
Identify the category of secondary storage media being used and the physical principle by which the binary state is read.
Optical storage; the photodiode detects variations in the intensity of reflected light caused by the scattering of the laser beam at the transition between microscopic pits and lands.
Magnetic storage; the photodiode measures the polarization angle of a magnetic field emitted by domains on the spinning platter.
Solid-state storage; the laser beam alters the resistance of floating-gate transistors, which is measured as a voltage difference.
Optical storage; the photodiode detects a frequency shift (Doppler effect) of the laser beam reflecting off physical grooves of varying depths.
76 exam-style questions on Edexcel GCSE Computer Science Hardware, covering Von Neumann architecture and FDE cycle, Secondary storage devices, and Embedded systems. Each one has a worked solution and a mark scheme showing where the marks go.