At what distance should an object be placed from a convex lens of power 4d?

Get the answer to your homework problem.

Try Numerade free for 7 days

Other Schools

CBSE 10 - Physics

f

Asked by durgeshsri8080 | 01 Aug, 2020, 06:43: AM

Option 2 : \(\frac{200}{3} \ cm\)

Free

10 Questions 10 Marks 10 Mins

CONCEPT:

• Lens: The transparent curved surface which is used to refract the light and make an image of any object placed in front of it is called a lens.
  • Convex lens: ​A lens having two spherical surfaces, bulging outwards is called a double convex lens (or simply convex lens).
  • It is thicker in the middle as compared to the edges.
  • Convex lenses converge light rays and hence, convex lenses are also called converging lenses.

• Lens formula is given by:

\(\frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)

• The magnification of the lens is given by:

Magnification (m) = v/u

Where u is object distance, v is image distance and f is the focal length of the lens

CALCULATION:

Given - Power of lens (P) = 4 D and image distance (v) = 40 cm

• The relation between the focal length and power of the lens is given by 

\(\Rightarrow f =\frac{100}{P}=\frac{100}{4}=25\, cm\)

• The lens formula is given by:

\(⇒ \frac{1}{v} - \frac{1}{u} = \frac{1}{f}\)

\(⇒ \frac{1}{u} = \frac{1}{v}-\frac{1}{f}\)

\(⇒ \frac{1}{u} =\frac{1}{{ 40}} - \left( {\frac{1}{{25}}} \right)=\frac{5-8}{200}=\frac{-3}{200}\)

\(\Rightarrow u=-\frac{200}{3}\)

India’s #1 Learning Platform

Start Complete Exam Preparation

Daily Live MasterClasses

Practice Question Bank

Mock Tests & Quizzes

Get Started for Free Download App

Trusted by 3.4 Crore+ Students