The question asks about the material used for modern submarine periscope lenses. This requires knowledge of material science and engineering applications, specifically for components exposed to harsh marine environments and requiring high optical performance and durability.
Correct Option: C) Sapphire — Modern submarine periscope lenses, especially the outer protective elements, are often made of sapphire. Sapphire offers superior hardness, scratch resistance, and optical clarity compared to traditional glass, making it ideal for the harsh marine environment and ensuring long-term optical performance.
The question asks about the technology that enables periscopes to be used at night. Periscopes are optical instruments used for observation from a concealed position. To function at night, they need a way to "see" in low or no visible light conditions. We need to identify which of the given options provides this capability.
B) Thermal imaging allows periscopes to be used at night by detecting the heat signatures (infrared radiation) emitted by objects. This technology works independently of visible light, making it effective in complete darkness, fog, or smoke.
The question asks for the essential optical component in a basic periscope. A periscope is an optical instrument that allows observation over, around, or through an object or obstacle. Its primary function is to change the direction of light rays to enable viewing from a different position.
C) Mirror — Mirrors are essential for a basic periscope as they reflect light at specific angles (usually 45 degrees) to change the path of light, allowing an observer to see objects that are otherwise obstructed.
The question asks about the feature that enables modern periscopes to offer a wider field of view. We need to consider the basic function of a periscope and how its design could be modified to achieve a broader observation area.
C) Rotating head — A rotating head allows the periscope to scan a full 360-degree horizon or a significant arc, thereby providing a much wider field of view than a fixed periscope. This is a crucial feature for surveillance and navigation in applications like submarines.
The question asks for the primary function of a periscope in a submarine. We need to understand what a periscope is and how it is used in the context of submarine operations.
Correct Option: B) Observing above the surface while submerged. This is the primary and most critical function of a periscope in a submarine, enabling situational awareness and stealth.
The question asks about the type of mirror used in a basic periscope. A periscope is an optical instrument that allows an observer to see objects that are not in their direct line of sight. Its primary function is to redirect light rays to achieve this.
C) Plane — Plane mirrors are used in basic periscopes because they provide a clear, undistorted, and unmagnified view of the object by simply reflecting the light rays to change their direction.