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4A practice exam › Unit A-8

4A A-8: Basic Concepts in Electrotechnology

94 practice questions in this unit. Each practice set pulls 20 at a time, so you keep seeing new questions as you go.

What this unit covers: AC and DC basics, magnetism, meters, motors and generators, transformers, distribution.

Exam theme: Electrical, controls and communication. Commonly reported share of the 100-question 4A exam: about 7 questions (unofficial; SOPEEC and ABSA do not publish per-unit counts). See the 4A exam breakdown.

2 free 4A A-8 questions, explained

Original exam-style questions written to the public syllabus, from our free public sample. They are not questions from a real exam.

1. In the structure of an atom, where are electrons located, and what type of electrical charge do they carry?

  • A. In the nucleus, carrying a negative charge
  • B. In shells orbiting the nucleus, carrying a positive charge
  • C. In shells orbiting the nucleus, carrying a negative charge
  • D. In the nucleus, carrying a positive charge
Show the answer and explanation

Answer: C. Electrons travel in shells (orbits) around the nucleus and carry a negative charge. Protons in the nucleus carry a positive charge, while neutrons are neutral. The attraction between negative electrons and positive protons keeps electrons bound to the atom.

Question ID KE-A08-C01-Q001 · Unit A-8: Basic Concepts in Electrotechnology · Report an error

2. Which device is specifically designed to protect sensitive computer and control systems from even a momentary interruption of AC power?

  • A. A load-shedding relay that isolates non-critical circuits during an outage
  • B. An automatic transfer switch (ATS) with open transfer capability
  • C. A key-interlocked tie circuit breaker connected to a standby bus
  • D. An uninterruptible power supply (UPS) with battery backup and inverter
Show the answer and explanation

Answer: D. An uninterruptible power supply (UPS) provides continuous power to sensitive systems, such as computers, controls, and communication equipment, that cannot tolerate even a momentary loss of power. It combines a rectifier, battery bank, and inverter to deliver seamless power during outages. An ATS with open transfer would still introduce a brief interruption, making it unsuitable for systems that require zero downtime.

Why the other options are not the answer

  • A. Load shedding drops non-critical loads; it does not keep critical loads powered through an outage.
  • B. An ATS with open transfer still breaks the supply briefly while it switches, which sensitive systems cannot tolerate.
  • C. A tie breaker switches the load between buses; it does not carry the load through the interruption itself.

Question ID KE-A08-C06-Q021 · Unit A-8: Basic Concepts in Electrotechnology · Report an error

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