FE Electrical & Computer Practice Question Solution included after investigation
CASE E-033 Β· FE

The Bode Plot That Lost 20 dB in One Decade

The low-frequency gain was 40 dB. One decade past the pole, the response was near 20 dB.

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Inspect, commit, prove, fix, and sign off.

Case E-033 engineering failure visual
HOW THIS WORKS

Think like
a real engineer.

Follow the investigation process used in the field β€” in five guided steps.

1

Inspect

Review the problem, diagram, and evidence.

2

Commit

Choose your hypothesis.

3

Prove

Run calculations and test your idea.

4

Fix

Select and validate a safe correction.

5

Sign Off

See the full debrief and key takeaways.

Case Brief

SAME PRINCIPLES. HIGHER STANDARDS.
PROBLEM STATEMENT

A first-order system has H(s)=100/(1+s/10). A technician plots a flat 40 dB magnitude because the numerator gain is 100. Measurement is about 37 dB at 10 rad/s and 20 dB at 100 rad/s. Diagnose the missing pole behavior, calculate the magnitude at 100 rad/s, and identify the asymptotic slope above the corner.

Control Systems Electrical & Computer Design Verification Root Cause Analysis Safe Correction
E-033
INVESTIGATION WORKSPACE WORK THROUGH THE CASE β€” YOUR CHOICES MATTER.
πŸ”’
DEBRIEF (LOCKED)

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to unlock the full debrief.

Find the root cause, confirm the fix, and see how this connects to the exam.

πŸ”’Root causeComplete the case
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πŸ”’Correct fixComplete the case
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πŸ”’Exam takeawayComplete the case
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CASE CLOSED Β· ENGINEERING VERDICT

What actually failed β€” and what should change.

What failed

A 40 dB DC gain was incorrectly extended to all frequencies.

What was missed

The pole at 10 rad/s changes the frequency response.

Corrected model

Use the corner frequency and pole/zero slope contributions when sketching Bode magnitude.

QUICK ANSWER

A first-order pole contributes approximately -20 dB per decade above its corner frequency. For H(s)=100/(1+s/10), the magnitude is 40 dB at low frequency, about 37 dB at 10 rad/s, and about 20 dB at 100 rad/s.

ENGINEERING TAKEAWAY

A first-order pole contributes approximately -20 dB/decade above its corner frequency and -45Β° phase at the corner.

CASE QUESTIONS

Questions this case should settle.

What Bode magnitude slope does one pole add?

Approximately -20 dB per decade above the pole frequency.

How far below the asymptote is a first-order pole at its corner?

About 3 dB.

NEXT FE PRACTICE QUESTION

The Higher-Gain Loop That Crossed Into Instability

Control Systems Β· 5–10 min

Continue Practice β†’
WHAT YOU’LL LEARN

Real failures. Lasting skills.

Each case is designed to build the judgment, analysis, and confidence you need for engineering exams β€” and beyond.

  • Apply core engineering concepts to real-world problems
  • Practice structured troubleshooting and analysis
  • Strengthen exam-ready thinking through realistic scenarios
COMMON QUESTIONS
Do I need prior knowledge to use these cases?

Basic subject familiarity helps, but every case is designed to teach through the investigation itself.

How long does a case take?

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Are the cases aligned with engineering exams?

Each case is mapped to a verified exam, subject, topic, and misconception before publication.

What happens after I complete a case?

The sealed debrief unlocks with the root cause, corrected reasoning, fix, and takeaway.