Two converging lenses, each of focal length 15.1 cm, are placed 40.4 cm apart, and an object is placed 30.0 cm in front of the first lens. Where is the final image formed?
The image is located ______ cm ---Location---a) in front of the second lens. b) behind the second lens. c)in front of the first lens.
What is the magnification of the system?
M = ______ ?
A :
We have been given following data :
f1 = 15.1 cm
f2 = 15.1 cm
L = 40.4 cm
p1 = 30 cm
Now,
using the lens equation : 1/p + 1/q =1/f
We will get:
1/30 + 1/q1 = 1/15.1
=> q1 = 30.4 cm
So,
p2 = L - q1
=> p2 = 10 cm
NOw,
Again Putting the value into the lens equation, we get:
1/10 + 1/q2 = 1/15.1
=> q2 = -29.61 cm
Hense ,
The final image is located at q2 = -29.61 cm
B :
magnification :
m1 = -q1/p1 => -30.4/30 = -1.01
m2 = -q2/p2 => -(-29.61)/10 = 2.961
Now,
Total magnification M = m1(m2) =(-1.01)*2.961 = -2.991
since the magnification is negative, hense the image is
inverted.
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