Single-Phase Transformers 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 does Lenz's Law state about the direction of an induced voltage/current?
It always opposes the change that produced it
It always reinforces and amplifies the change that produced it
It has no defined direction relative to the change that produced it
It only applies to DC circuits, not AC transformers
Answer: It always opposes the change that produced it — Lenz's Law states that the direction of an induced voltage (and the current it drives) always opposes the change that produced it.
Easy
2. Which property is specifically responsible for a transformer transferring energy from its primary winding to its separate secondary winding?
Mutual inductance
Self-inductance only
Direct electrical (conductive) connection between windings
Capacitive coupling between windings
Answer: Mutual inductance — Mutual inductance is the property by which a changing current in the primary winding induces a voltage in the separate, magnetically linked secondary winding, with no direct electrical connection between them.
Medium
3. Name the "magnetic equivalent" of electromotive force, calculated as the product of current and number of turns, that establishes magnetic flux.
Answer: magnetomotive force — Magnetomotive force (mmf) is the "magnetic equivalent" of electromotive force, the driving quantity that establishes magnetic flux, calculated as current multiplied by number of turns.
