What Type of Mirror Is Used in a Periscope?A periscope is a fascinating optical instrument that allows people to see over or around obstacles. Commonly used in submarines, trenches, and even by curious children playing spy games, a periscope functions by reflecting light from one point to another. The main components that make this possible are mirrors but not just any kind. This topic will explain the type of mirror used in a periscope, how it works, and why that specific type is ideal for the job.
What Is a Periscope?
A periscope is a tube-shaped device that enables someone to view objects from a hidden or protected position. It typically consists of two mirrors placed at 45-degree angles at each end of the tube. When light hits the top mirror, it is reflected down the tube to the second mirror, which reflects the image into the viewer’s eye.
Periscopes have been used in military settings, such as on submarines and in war trenches, as well as in non-military uses like observing wildlife or crowds discreetly.
The Type of Mirror Used in a Periscope
The type of mirror used in a periscope is a plane mirror.
What Is a Plane Mirror?
A plane mirror is a flat-surfaced mirror that reflects light evenly. When light rays hit its surface, they bounce off at the same angle, creating a clear and accurate reflection of the original object. This type of mirror does not distort the image, which is essential for accurate viewing through a periscope.
Why Plane Mirrors Are Ideal for Periscopes
There are several reasons why plane mirrors are chosen for periscopes
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Simple Reflection They reflect light in a straightforward manner, preserving the shape, size, and direction of the image.
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No Magnification Unlike concave or convex mirrors, plane mirrors do not magnify or shrink the image. This helps maintain a true representation of the object.
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Easy to Align Their flat surface makes them easier to position at precise angles, which is critical for the periscope’s effectiveness.
Mirror Placement and Angle
For a periscope to work properly, the two plane mirrors must be placed at 45-degree angles relative to the direction of the tube. This arrangement ensures that the light entering from the top is directed down to the lower mirror and finally to the observer’s eye.
The reflection process works as follows
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Light from the object enters the periscope and hits the first mirror.
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The first mirror reflects the light downward.
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The second mirror, positioned at another 45-degree angle, reflects the light horizontally to the viewer.
This simple use of reflection makes periscopes effective tools for indirect viewing.
Are Other Types of Mirrors Ever Used?
Though plane mirrors are the standard choice, some advanced or modern periscopes may use prisms instead of traditional mirrors. Prisms are optical elements that also reflect light, often with even higher precision and less image distortion. However, in basic and educational models, plane mirrors remain the most common and cost-effective option.
Real-World Applications of Periscopes
Periscopes have a variety of uses
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Submarines Sailors use periscopes to observe the surface of the water while staying submerged.
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Tanks and Bunkers Soldiers can look outside without exposing themselves to danger.
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Scientific Observation Used for discreet observation in research settings.
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Recreational Use Often found in toys and teaching kits to help children learn about light and reflection.
Each of these applications benefits from the clear, reliable reflection provided by plane mirrors.
How Periscopes Demonstrate the Laws of Reflection
Periscopes are a great way to understand the laws of reflection in physics. These laws state that
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The angle of incidence equals the angle of reflection.
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The incident ray, reflected ray, and the normal all lie in the same plane.
In a periscope, plane mirrors follow these principles perfectly, ensuring that the image reaches the viewer without distortion or loss of detail.
Simple DIY Periscope Using Plane Mirrors
You can make a simple periscope at home with basic materials
Materials Needed
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Two plane mirrors
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A cardboard tube or two pieces of stiff cardboard
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Scissors and tape
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Ruler and pencil
Steps
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Cut two square holes near each end of the cardboard tube.
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Tape a plane mirror inside each hole at a 45-degree angle.
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Align the mirrors so that they reflect light from the top hole to the bottom hole.
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Look through the lower opening and observe how the image from the top is reflected clearly.
This experiment helps illustrate how plane mirrors are essential to periscope design.
Summary Key Points to Remember
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Plane mirrors are the type of mirrors used in periscopes.
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They are placed at 45-degree angles to reflect light from one end to the other.
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Their flat surface allows for accurate, undistorted images.
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Periscopes are used in military, science, and educational settings.
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Understanding how mirrors work in a periscope reinforces basic optics principles like the law of reflection.
The use of plane mirrors in periscopes is a brilliant example of how simple tools and basic scientific principles can be combined to solve real-world problems. Whether you’re looking at military equipment or a child’s science project, the function remains the same giving us a clear line of sight where we otherwise couldn’t see. Thanks to the reliable reflection of light by plane mirrors, periscopes continue to be valuable and fascinating instruments in both everyday and specialized applications.
