Question

Rays that are used in taking photos during conditions of smoke, darkness is

• A. X-rays
• B. Gamma rays
• C. Ultraviolet rays
• D. Infrared rays

Hint:

Infrared rays are useful for night vision and thermal imaging because they detect heat radiation.

Answer 1

The Correct Option is D

Concept:
Infrared rays are electromagnetic waves having wavelength longer than visible red light. They are associated with heat radiation and are useful in night vision, thermal imaging, and photography in darkness or smoky conditions.

Step 1: Understand the condition given.
The question mentions: \[ \text{smoke and darkness} \] In such conditions, ordinary visible light photography may not work properly. So we need radiation that can help imaging even when visible light is weak or blocked.

Step 2: Recall use of infrared rays.
Infrared rays are used in: \[ \text{night vision cameras} \] \[ \text{thermal imaging} \] \[ \text{photography in fog, smoke, and darkness} \] They can detect heat emitted by objects.

Step 3: Check the options.
Option (A) X-rays are used mainly for medical imaging and detecting internal structures.
Option (B) Gamma rays are highly energetic and not used for ordinary photography in smoke or darkness.
Option (C) Ultraviolet rays are not used for night vision photography.
Option (D) Infrared rays are correct. Hence, the correct answer is: \[ \boxed{(D)\ \text{Infrared rays}} \]