Q. Explain Physical Characteristics of magnetic disk?

Figure below lists main features that differentiate among different types of magnetic disks. First head may either be fixed or movable either respect to radial direction of platter. In a fixed-head disk there is one read-write head for each track. All of heads are mounted on a rigid arm which extends across all tracks. These kinds of systems are rare today. In a movable-head disk there is just one read-write head. Again head is mounted on an arm. Since head should be able to be positioned above any track arm can be retracted or extended for this purpose.

Figure:  Physical characteristics of Disk Systems