Full dark adaptation, such as going from constant light to sudden darkness when turning out one's bedroom lights, takes about _____ minutes.

• A. 10
• B. 30
• C. 60
• D. 90

Answer: (B)

Verified step by step guidance

1. Understand the concept of dark adaptation: Dark adaptation refers to the process by which our eyes adjust to low light conditions after being exposed to bright light. This involves the regeneration of photopigments in the rods of the retina, which are responsible for vision in dim light.
2. Recognize the role of rods and cones: In bright light, cones are primarily active, allowing us to see color and detail. In darkness, rods become more active, enhancing our ability to see in low light. The transition from cone-dominated vision to rod-dominated vision is what constitutes dark adaptation.
3. Consider the time frame for full dark adaptation: Research indicates that full dark adaptation, where the eyes are fully adjusted to darkness, typically takes around 30 minutes. This is the time required for the rods to reach maximum sensitivity.
4. Evaluate the options given: The options provided are 10, 30, 60, and 90 minutes. Based on the understanding of dark adaptation, 30 minutes is the most accurate duration for full adaptation.
5. Conclude with the correct choice: Given the explanation and typical duration for dark adaptation, the correct answer is 30 minutes.