Test Your EQ
— Issue #148
Each month, Test Your EQ presents
some basic engineering problems for you to test
your Engineering Quotient. What's your EQ?
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Problem 1—A
computer with a 64-bit wide data bus uses 1Mbit ×
1 DRAM memory chips. What is the smallest memory in bytes
that this computer can have?
Answer
Problem 2—An oil-filled capacitor
consists of two plates separated by a dielectric made
of oil with a dielectric constant of 10. The capacitance
is 10µF and it is charged to 10 volts. The oil is
drained, leaving air between the plates. The capacitance
falls to 1µF. Does the stored energy level change?
If so, where did the extra energy come from or go to?
Answer
Problem 3—You wish to
design a 4-way set associative cache with a total of 8
kilobytes of data cache. Addresses are 16 bits in length.
How many address bits will be in the tag field?
Answer
Problem 4—The greatest common divisor
of two positive integers x and y, written gcd (x, y),
is the largest integer that divides evenly both x and
y. Write a recursive algorithm to find the GCD of two
numbers.
Answer
Problem 5—What is the overall gain
of the following circuit? The opamp has an open loop gain
of 2.
Answer
Problem 6—"CD quality" sound is
represented by using 2 channels (stereo), with each channel
taking 44,100 samples per second and using 16 bits per
sample. An alternative is "radio quality" sound. This
representation uses only one channel (mono) at a sample
rate of 22,050 samples per second and only 8 bits per
sample. Approximately how many hours of sound recording
can be stored in on a 1 Gigabyte disk in each of these
representations? A 1 Gigabyte disk can hold approximately
8 billion bits.
Answer
Problem 7—You
have a small box whose internal workings you can't see,
but the box has two terminals. You measure these two terminals
with a voltmeter, and it measures precisely 1V. You short
the two terminals with an ammeter, and it reads precisely
1A. You then conclude the internal circuit is either a
Thevenin source (an ideal 1V voltage source with a 1-ohm
series resistor) or a Norton source (an ideal 1A current
source with a 1-ohm shunt resistor). Using standard laboratory
equipment, how could you determine which one it is?
Answer
Problem 8—Which is the best of
the optic fibers in terms of bandwidth: multimode step-index,
multimode graded index and single mode? Why?
Answer
Published: October-2002
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