An object O is positioned along the optical axis at a distance of 30 cm from a p

Question

An object O is positioned along the optical axis at a distance of 30 cm from a positive thin lens A with focal length fa 10cm. A second positive thin lens B, with focal length fs 90cm, is positioned a distance 60 cm from lens A along the optical axis in the direction away from O. The configuration is illustrated in the diagram below. Assume paraxial optics throughout this problem. Give quantitative answers as numerical values. (a) Determine the location of the image of the object formed by lens A. Construct a ray diagram showing the location and the height of this image, using the figure below. Indicate whether this image is real or virtual, and whether it is right-side up or inverted. What is the transverse magnification of this image? b) Take the image formed by lens A as the object for lens B, and determine the location of the image formed by lens B. Construct a ray diagram showing the location and height of this image, also using the figure below. Indicate whether this image is real or virtual, and whether it is right-side up or inverted relative to the image formed by lens A. What is the transverse magnification of this image relative to the image formed by lens A (c) What is the overall transverse magnification of the two-lens combination? What does the object look like when seen through this configuration from the right? 30 cm 60 cm -

Explanation / Answer

(A) object distance, p1 = 30 cm

f1 = 10 cm

1/f1 = 1/p1 + 1/q1

1/10 = 1/30 + 1/q1

q1 = 15 cm

location: 15 cm right of lens A.

q1 is +ve so image is real.

m1 = - q1/ p1 = - 0.5

magnification is -ve hence image is inverted.

height is half of height of object.

(B) now this image will act as object for lens B,

p2 = 60 - 15 = 45 cm

f2 = 90 cm

1/90 = 1/45 + 1/q2

q2 = - 90 cm

image is formed 90 cm left of the lens B.

m2 = -q2 / p2 = 2

image is virtual, uprigt.

(C) m = m1 m2 = - 1

object will be of same height and inverted

and will be formed at the location of object.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.