, the power dissipated P,
in watts, will be given by the equation:
The examination consists of two separate exercises. Marks will be divided equally between the two exercises.
The two exercises are related, but can be attempted independently (i.e. you do not have to complete the first in order to attempt the second, or vice versa). It is strongly recommended that you plan your allocation of time between the two exercises carefully in advance, and stick to this allocation during the exam.
When you have completed this exam, your report should be emailed to the address:
exam3a@ugmail.eeng.dcu.ie
Do not email multiple copies of the report. If you experience difficulties in emailing the report, please ask for help from an invigilator.
If a voltage V, in volts, is applied to a resistor of
resistance R, in , the power dissipated P,
in watts, will be given by the equation:
The program VPWR.C is supposed to prompt for and read in values for V and R, and then calculate and print out the corresponding power dissipation (P). It should do this repeatedly until a value of zero is entered for V, when it should terminate.
The program has various defects. You are required to correct all defects you can identify. For all changes that you make, the report should contain a clear statement of the change and a specific explanation of your rationale for the change. Of course, if you are making several similar or related changes, you may discuss these as a unit.
When you have reached the point where you think the program should work, then you should test it, and report on these tests. Carry out, and report on, further corrections if necessary.
Note carefully that you must not simply present a version of the program rewritten from scratch. You are required to identify the specific defects in the program you have been given.
Develop a program which will prompt for, and read in, values
for resistance (R), applied voltage (V), and maximum power
rating ( 
) of a resistor. For this set of values, the
program should then calculate, and output, the actual
power dissipation in accordance with the equation given in
exercise 1. The program should also compare this actual
dissipation with the rated maximum dissipation for the
resistor. If the actual dissipation is less than or equal to
the maximum, the program should output PASS; otherwise it
should output FAIL. Having completed this computation for
one resistor, the program should then offer the user a choice
between terminating, or repeating the calculation for a new
resistor. The program should continue indefinitely (i.e. for
as long as the user continues to request this).
You may develop this program from scratch, or, if you wish, you may reuse and augment your corrected program from Exercise 1. In either case, your program must conform to the following restrictions:
Test your program severely. Record all test results.