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periscope

Primary Information
Secondary Information

Definition

A periscope is an optical instrument that uses a system of mirrors or prisms to reflect light around an obstacle and allow the observer to see objects that would otherwise be hidden.

The most common type of periscope uses two mirrors that are angled at 45 degrees. Light from an object strikes the top mirror and is reflected down the periscope tube. The bottom mirror reflects the light back up to the observer's eye.

Periscopes can also be made with prisms instead of mirrors. Prisms bend light, which allows them to be used to reflect light around corners or other obstacles.

Periscopes are often used in submarines, tanks, and other vehicles that need to be able to see above or around obstacles. They are also used by firefighters, soldiers, and other people who need to be able to see in difficult or dangerous conditions.

How can the word be used?

The ship's periscope was damaged in the storm.

periscope

Different forms of the word

Noun:

  • periscope (an instrument for observing objects over, around, or through an obstacle).
  • periscopic (of or relating to a periscope).

Etymology

The word "periscope" is derived from the Greek words "peri" (around) and "skopein" (to look). The first recorded use of the word "periscope" in English was in 1854.

Question

When might a periscope be useful?

AQA Science Exam Question and Answer

Question:

Explain the scientific principles underlying the operation of a periscope. Describe how the arrangement of mirrors in a periscope allows for the viewing of objects that are not in the direct line of sight.

Answer:

A periscope operates based on the principles of reflection and the properties of light. It consists of two parallel mirrors positioned at a specific angle to each other. When light enters the top mirror at a certain angle, it undergoes reflection and bounces off the mirror's surface. This reflected light then strikes the second mirror at the same angle, resulting in another reflection that redirects the light towards the viewer's eyes.

The key principle behind the periscope's function is the angle of reflection. Since the mirrors are positioned parallel to each other, the light entering the top mirror and reflecting off the bottom mirror maintains the same angle relative to the perpendicular. This allows the viewer to observe objects that are not within their direct line of sight, such as objects above or around obstacles.

In applications like submarines or military reconnaissance, periscopes enable observation while keeping the observer hidden from view. This arrangement of mirrors allows light to travel a longer path, enabling the viewing of objects that would otherwise be obstructed from view.