Which of these does NOT have an optical lens?

Correct option is D

The correct answer is (D) Stethoscope.

A stethoscope is a medical device used to listen to internal sounds of the body, particularly the heart and lungs. Unlike the other options, a stethoscope does not contain any optical lens or mirror; instead, it relies on acoustic properties to transmit sound through tubes to the healthcare professional's ears. The diaphragm and bell of the stethoscope capture sound waves, which are then amplified and directed through the earpieces.

On the other hand:

• Microscope: Utilizes a series of optical lenses to magnify small objects, enabling detailed observation of tiny structures.
• Periscope: Uses mirrors or lenses to reflect and direct light, allowing observation from a different vantage point.
• Telescope: Employs lenses or mirrors to gather and magnify distant light sources, making it essential for astronomical observations.