USCG Exam PracticeLight List, ranges, and light characteristics
What distinguishes an Isophase (Iso) light from both a Flashing (Fl) and an Occulting (Oc) light?
- A. The Iso light has a brighter flash superimposed on a fixed light
- B. The Iso light has a duration of light shorter than its duration of darkness
- ✓ The Iso light has equal durations of light and darknessCorrect
- D. The Iso light has a duration of light longer than its duration of darkness
Why C is correct
Isophase (Iso) is defined by equal periods of light and darkness. Flashing lights have light shorter than darkness, and Occulting lights have light longer than darkness. (Light List — Iso, Fl, Oc)