Draw a ray diagram of image formed when an object kept at the distance 50 cm by convex lens having focal length 20 cm.Write two nature of image. Calculate the power of lens.
Answers
Given that
The height of object = 5cm
Position of object, u = – 25cm
The focal length of the lens, f = 10 cm
We need to find
The position of the image, v =?
Size of the image
Nature of the image
Formula
We know that
1/v – 1/u = 1/f
Substituting the known values in the above equation we get,
1/v + 1/25 = 1/10
=> 1/v = 1/10 – 1/25
=> 1/v = (5 – 2)/50
Hence, 1/v = 3/50
So, v= 50/3 = 16.66 cm
Therefore, the distance of the image is 16.66 cm on the opposite side of the lens.
Now, we know that
Magnification = v/u
Hence, m = 16.66/-25 = -0.66
Also, we know that
m= height of image/height of the object
Or, -0.66 = height of image / 5 cm
Hence, height of image = -3.3 cm
The negative sign of the height of the image depicts that an inverted image is formed.
So, the position of image = At 16.66 cm on the opposite side of the lens
Size of image = – 3.3 cm at the opposite side of the lens
Nature of image – Real and inverted