(a) (i) Draw a ray diagram of a reflecting telescope (Cassegrain) and explain the formation of image. State two important advantages that a reflecting telescope has over a refracting telescope. (ii) In a refracting telescope, the focal length of the objective is 50 times the focal length of the eyepiece. When the final image is formed at infinity, the length of the tube is $102 \text{ cm}$. Find the focal lengths of the two lenses. OR (b) (i) Write any two advantages of a compound microscope over a simple microscope. Draw a ray diagram for the image formation at the near point by a compound microscope and explain it. (ii) A thin planoconcave lens with its curved face of radius of curvature $R$ is made of glass of refractive index $n_1$. It is placed coaxially in contact with a thin equiconvex lens of same radius of curvature of refractive index $n_2$. Obtain the power of the combination lens.

Year	Paper Code	Set	Position
CBSE 2025	Series 55-5	Set 1	Question 33
CBSE 2025	Series 55-5	Set 2	Question 32
CBSE 2025	Series 55-5	Set 3	Question 31

• Step 1: Stating the fundamental formula / law statement (+1 Mark)
• Step 2: Intermediate mathematical substitution or proof steps (+1 Mark)
• Step 3: Correct final value or conclusion with mandatory SI units (+1 Mark)