Convex Mirror

Have you ever noticed the function of rear view mirrors of the car? When your parents are driving car on highway and they want to take turn towards right side, they need to see if any vehicle is there behind your car or not. For this they won’t turn their neck, they will just see through the mirror fixed outside car. Rear view mirrors are most essential part of driving while driving any vehicle. Which type of mirrors is used in it? See fig. 1 below

As shown in fig.2 the spherical mirror whose internally bulged surface is polished such that externally bulged surface become reflecting is known as convex mirror. They are cut from sphere of glass and polished with certain materials so that it acts as reflecting surface.

Convex mirrors cannot form image on the screen, hence they always produced virtual image of object. These images appear upright or erected. i.e. when you hold candle very close to convex mirror, magnified and erected image is obtain behind the mirror. As this image can’t be produce on screen it is virtual and erect.

When parallel beam of light falls on convex mirror, after reflection all rays moving away but appears to be distributed from same point behind mirror, this point is known as focus of mirror. Due to this ability convex mirrors are also called as diverging mirror. See the fig below.

Now let’s discuss some important conditions of image formation due to convex mirrors.

  • Image formed by convex mirror is always behind the mirror.
  • As the image can’t be located on screen, it is always a virtual image.
  • Image does not rotated by any angle; hence it appears upright, i.e. erected.

Following are some important applications of convex mirror;

  • Rear view mirror of vehicle: To see the passage of road and vehicles running behind our vehicles, we need to fix a convex mirror of suitable size outside the vehicle.
  • Street light reflectors: For visibility of traffic signs mounted everywhere on road, and to increase the reach of street light convex mirrors are used.
  • Telescope: Distinct object can be brought to our visible range by using big convex mirrors.
  • In Security cameras: To increase the width of surveillance of CCTV’s they come with convex mirrors so that more area can be covered.

Q. What do you mean by convex mirror?

Ans: Spherical mirrors which bulges (curved) externally such as its bulged surface becomes reflecting, called as convex mirror.

Q. What types of images can be produced by convex mirror?

Ans: Concave mirror can produce virtual and erected image.

Q. What do you mean by erected image?

Ans: When image of object on screen is appear to be same as object, called as erected image.

Q. Why convex mirror is also called as diverging mirror?

Ans: When parallel beam of light falls on convex mirror, after reflection all rays moving away but appears to be distributed from same point behind mirror, due to this property convex mirror is also known as diverging mirror.

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