A luminous object is one that

Step 1: Analyze the question The question asks for the definition of a luminous object in the study of light.

Step 2: Explain the concept In Physics, objects are classified by how they relate to light:

• Luminous objects produce their own light. Examples are the Sun, stars, a lit candle, and a glowing electric bulb.
• Non-luminous objects do not produce light. We see them only because they reflect light from luminous sources. Examples are the Moon, a book, a table, and a mirror.

Step 3: Evaluate each option

• A. "Gives off dim blue-green light only in the dark" describes bioluminescence or phosphorescence, which is not the general definition of luminous. ❌
• B. "Gives out light of its own" is exactly the definition of a luminous object. ✅
• C. "Shines by reflected light only" describes a non-luminous object, like the Moon. ❌
• D. "Glows only in the presence of light" does not describe a source of its own light. ❌

Step 4: Answer The correct option is B.

Tip: Remember that luminous contains the idea of luminance, or light. A luminous object is a light maker. A non-luminous object is only a light reflector. Whenever you see the Moon in a WASSCE question, think "non-luminous, because it reflects sunlight."