CU Boulder 01-22-2003
ECE Dept
Data Storage Technology
ECEN 5018
Homework #1
(Due Wednesday, January 29, 2003)
Problem 1
The areal density of a magnetic disk drive has been found to satisfy the following model
where y is a variable representing the year.
1. If the progress continues at this pace, what will be the areal density in year 2010?
2. Plot the areal density G from 1970 to 2010 using logarithmic scale for G. What are the slopes of the two segments of the curve?
3. If there will be a dramatic improvement in magnetic disk drive technology in 2005 so that the areal density will increase 80% every year, then find the new expression of G for y³2005 and determine the predicted value of G for year 2010.
Problem 2
What are the advantages of magnetic disk drives over semiconductor memory?
Problem 3
Travelstar disk drive by IBM has a linear bit density of 127.2 Kb/in and a track density of 7257 track/in.
1. What is its areal density in Mb/mm2 (1in = 2.54cm)?
2. Use the model G(Mb/in2) = 100x100.178(y-1990) to find approximately the year this drive was developed.
Problem 4
Two magnetic poles with strengths m1 = m2 = 0.803 A-m. What is the distance between them if the force that each pole exerts on the other is F = 10-4 N?
Problem 5
Ampere's law is given by
where H is the magnetic field magnitude, i is the electrical current, and l is a closed path over which the integration is performed.
1. For a straight wire with current i, find H at a distance r from this wire.
2. Plot H as a function of r if i=0.5 A. (Use 0<r<1 m.)
3. At what distance r the magnitude of H is 0.5 Oe?