Explain the reflective telescope with diagram and write its advantages over refractive telescope. On what factors does its resolving power depend?

Advantages: (i) It is free from chromatic aberration. (ii) Its resolving power is greater than refracting telescope due to larger aperture of mirror. The factor on which its resolving power depend are as follows- The resolving power of a telescope depends on the diameter of the telescope's light-gathering apparatus, or objective. In a refracting telescope, the objective lens is the first lens the light passes through. In a reflecting telescope, the objective is the telescope's primary mirror.

A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 50 cm . What is the magnifying power of telescope when image is at infinity and image is formed at least distance of distinct vision?

Here f o = 140 c m , f e = 5 . 0 c m (a) In normal adjustment,magnifying power = f o f e = 140 - 5 = - 28 (b) When final image is at the least distance of distinct vision. Magnifying power = - f o f e = 140 - 5 1 + 5 25 = - 33 . 6 ..

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Ray Optics and Optical Instruments>Nagaland Board-2018>Q 2

EASY

12th Nagaland Board

IMPORTANT

Earn 100

Draw a labelled diagram of an astronomical telescope and explain its working. Give an expression for its magnifying power.

Important Questions on Ray Optics and Optical Instruments

EASY

12th Nagaland Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Ray Optics and Optical Instruments>Nagaland Board-2019>Q 3

A ray of light is incident on one face of a prism and emerges out from the other face. Draw a ray diagram and derive an expression for refractive index of the material of the prism.

EASY

12th Nagaland Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Ray Optics and Optical Instruments>Nagaland Board-2019>Q 4

Derive the lens maker’s formula for a thin double convex lens. Why is it called so?

MEDIUM

12th Nagaland Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Ray Optics and Optical Instruments>Nagaland Board-2019>Q 5

Draw a neat ray diagram to show the image formation in a compound microscope. Define its magnifying power and derive an expression for it, when the final image is at near point of eye.

EASY

12th Nagaland Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Ray Optics and Optical Instruments>Nagaland Board-2020>Q 6

A convex lens of focal length

40 cm

is in contact with a concave lens of focal length

25 cm

. The power of the combination is

EASY

12th Nagaland Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Ray Optics and Optical Instruments>Nagaland Board-2020>Q 7

Deduce the relation between object and image distance in terms of refractive index of the medium and the radius of curvature of curved spherical surface.

EASY

12th Nagaland Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Ray Optics and Optical Instruments>Nagaland Board-2020>Q 8

If