Light Characteristics Practice Questions

1. A FIXED light (F) is described as:

• A.A light that shows a single flash at regular intervals
• B.A continuous, steady light with no interruptions✓
• C.A light that is on longer than it is off
• D.A light that alternates between two colors at equal intervals

Why: A Fixed (F) light is a continuous, uninterrupted light — it does not flash or occult. It remains on at constant intensity.

2. An OCCULTING light is one in which:

• A.The period of light is less than the period of darkness
• B.The period of light is equal to the period of darkness
• C.The period of darkness is less than the period of light✓
• D.The light flashes more than 60 times per minute

Why: An Occulting (Oc) light is on MORE than it is off — the duration of darkness (eclipse) is always less than the duration of light. This is the opposite of a flashing light.

3. A QUICK light (Q) flashes at approximately what rate?

• A.15 flashes per minute
• B.30 flashes per minute
• C.50 to 60 flashes per minute✓
• D.120 flashes per minute

Why: A Quick (Q) light flashes at a rate of 50 to 60 times per minute. Very Quick (VQ) lights flash 100 to 120 times per minute.

4. The notation 'Mo(A)' on a chart or Light List indicates a light that:

• A.Shows alternating red and white sectors
• B.Transmits Morse code letter A (dot-dash) in flashes✓
• C.Is a quick-flashing amber light
• D.Shows a group of flashes equal to 'A' on the phonetic alphabet

Why: Mo(A) means a Morse code light showing the letter A: one short flash followed by one long flash, repeated. Safe water marks commonly use Mo(A).

5. Which light characteristic can indicate an ISOLATED DANGER mark in U.S. waters?

• A.Fixed white
• B.Quick flashing white
• C.Group flashing (2) white — Fl(2) W✓
• D.Isophase red

Why: Isolated danger marks, when lighted, show a group flashing light with two flashes — Fl(2) — in white. This distinguishes them from lateral marks.