The figure shows the image formation of an object in simple microscope. Derive an equation for magnifying power of the simple microscope.

Magnifying power is the ratio of the angle subtended at the eye by the image at the near point, to the angle subtended by the object, at least distance of distinct vision. In the given figure, the image is formed at the near point. According to the figure, the angle subtended by the image at the eye is β and the angle subtended by the object at the unaided eye is α . Let the object distance be u = O Q and the image distance be D = O Q 1 . Hence, the magnifying power can be given as: M = Angle subtended by the image at the eye through the lens Angle subtended by the object at least distance of distinct vision ⇒ M = β α From the triangle P Q O , tan β = P Q Q O ⇒ β = P Q Q O ∵ β is very small . . . 1 From the triangle P Q 1 O , tan α = P Q 1 O Q 1 ⇒ α = P Q 1 O Q 1 ∵ α is very small ⇒ α = P Q O Q 1 ∵PQ 1 =PQ . . . 2 From equations 1 and 2 , the magnifying power can be calculated as: M = β α ⇒ M = P Q Q O × O Q 1 P Q ⇒ M = O Q 1 O Q = D u From the lens formula: 1 f = 1 v - 1 u 1 f = - 1 v + 1 u ( from sign convention ) - 1 D + 1 u = 1 f ⇒ - 1 + D u = D f ⇒ 1 + D f = D u ⇒ M = 1 + D f ∵ M = D u Hence, the formula for magnifying power of a simple microscope is M = 1 + D f .

Embibe Experts Solutions for Chapter: Ray Optics and Optical Instruments, Exercise 1: Kerala Board-2019

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Embibe Experts Physics Solutions for Exercise - Embibe Experts Solutions for Chapter: Ray Optics and Optical Instruments, Exercise 1: Kerala Board-2019

Attempt the free practice questions on Chapter 9: Ray Optics and Optical Instruments, Exercise 1: Kerala Board-2019 with hints and solutions to strengthen your understanding. EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS solutions are prepared by Experienced Embibe Experts.

Questions from Embibe Experts Solutions for Chapter: Ray Optics and Optical Instruments, Exercise 1: Kerala Board-2019 with Hints & Solutions

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12th Kerala Board

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 9 - Ray Optics and Optical Instruments>Kerala Board-2019>Q 6

A small telescope has an objective lens of focal length $140 cm$ and an eyepiece of focal length $5 cm$ . What is the magnifying power of the telescope for viewing distant objects when the telescope is in normal adjustment.