If you mean in the periscope, two.
The periscope, and I believe they have a lot more than 2 mirrors.
Mirrors help illusions because mirrors make stuff look like if nothing is there.
A periscope is the instrument used in a submarine to see above the surface of water. It works by using mirrors to reflect light down into the submarine while allowing for observation of the surface without exposing the submarine itself.
The fins help steer the submarine; making it be able to turn left or right.
The instrument used in submarines to observe the surface of water is called a periscope. A periscope consists of a long tube with mirrors at each end, allowing the viewer to see objects above the water's surface while the submarine remains submerged. The periscope's mirrors reflect light from the surface down the tube to the viewer, providing a view of the surroundings without the need to surface the submarine.
No
because they reflect
submarine are important because it help alot of people doring world war 1.
They use convex mirrors to give a wider view.
A cars mirrors (minus the sun-visor mirrors) help you to safely navigate through the road. Side mirror & rear view mirrors will help you see objects & people without turning your head all the time. Note that these mirrors do have blind spots. You will have to double check before you take any action. Be safe!
Concave mirrors are typically used in street lights. These mirrors help to gather and reflect light in a controlled manner, directing the light downwards to illuminate the street below and increase visibility for drivers and pedestrians.