Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard
  1. Home
  2. Engineering
  3. In an experiment a convex lens of focal length
# Engineering

In an experiment a convex lens of focal length 15 cm is placed coaxially on an optical bench in front of a convex mirror at a distance of 5 cm from it. It is found that an object and its image coincide, if the object is placed at a distance of 20 cm from the lens. The focal length of the convex mirror is .

Answers (1)
S Safeer PP

 Given focal length of lents (f) = 1.5 cm  

Object distance u = - 20 cm ,  f = 15 cm

We know that \frac{1}{f}=\frac{1}{v}-\frac{1}{u}=\frac{1}{v}=\frac{1}{f}+\frac{1}{u}

\frac{1}{v}=\frac{1}{15}-\frac{1}{20}

\frac{1}{v}=\frac{4-3}{60}

v = 60 cm 

The image 1 gets formed at 60 cm to ghe right of the lens and it will be inverted.

Therefore, Distance between lens and mirror will be

d = image distance(v) - radius of curvature of convex mirror

s = 60 - 2f 

\Rightarrow    2f = 60 - 5

f=\frac{55}{2}=27.5\ cm(convex mirror) 

Similar Questions

Latest Asked Questions

Most Viewed Questions

Preparation Products

Knockout JEE Main (Six Month Subscription)

- AI Coach Study Modules, - Unlimited Mock Tests, - Study Improvement Plan.

₹ 9999/- ₹ 8499/-
Buy Now
Knockout JEE Main (Nine Month Subscription)

- AI Coach Study Modules, - Unlimited Mock Tests, - Study Improvement Plan.

₹ 13999/- ₹ 12499/-
Buy Now
Test Series JEE Main 2024

Chapter/Subject/Full Mock Tests for JEE Main, Personalized Performance Report, Weakness Sheet, Complete Answer Key,.

₹ 7999/- ₹ 4999/-
Buy Now
Knockout JEE Main (One Month Subscription)

- AI Coach Study Modules, - Unlimited Mock Tests, - Study Improvement Plan.

₹ 7999/- ₹ 4999/-
Buy Now
Knockout JEE Main (Twelve Months Subscription)

- AI Coach Study Modules, - Unlimited Mock Tests, - Study Improvement Plan.

₹ 19999/- ₹ 14499/-
Buy Now
Boost your Preparation for JEE Main 2021 with Personlized Coaching
Start Now
 
Exams
Articles
Questions