Single-Phase AC Theory & Waveforms is one of 9 topics in the Grade 11 Electrical Technology CAPS syllabus, covered across 3 lessons on Study Vault. Below are real practice questions from this topic with full worked answers.
Sample practice questions
Easy
1. What is the fundamental difference between AC and DC?
AC periodically reverses direction; DC flows in one constant direction only
AC and DC are identical, differing only in naming convention
DC periodically reverses direction; AC flows in one constant direction only
AC can only be generated mechanically, while DC cannot
Answer: AC periodically reverses direction; DC flows in one constant direction only — Direct current (DC) flows in one constant direction only, while alternating current (AC) periodically reverses direction, rising and falling in a repeating pattern.
Easy
2. What is a key practical motivation for using AC rather than DC in power generation and distribution?
AC voltage can be easily stepped up or down using a transformer, enabling efficient high-voltage transmission
DC is impossible to generate using rotating machinery
AC requires no insulation on conductors, unlike DC
Transformers can only step up or down DC voltage, not AC
Answer: AC voltage can be easily stepped up or down using a transformer, enabling efficient high-voltage transmission — AC voltage can be easily stepped up or down using a transformer, making it practical to transmit power at high voltage (reducing losses) and step it back down for safe use, a flexibility DC systems of the same era could not easily match.
Medium
3. Name the law that states a voltage is induced in a conductor whenever it experiences a changing magnetic flux.
Answer: Faraday's Law — Faraday's Law states that a voltage is induced in a conductor whenever it experiences a changing magnetic flux, whether from relative motion or a changing field.
