Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • Engineering
  • Need clarity, kindly explain! You are asked to design a shaving mirror assuming that a person keeps it 10 cm from his face and views the magnified image of the face at the closest comfortable distance of 25 cm. The radius of curvature of the mirror w

 You are asked to design a shaving mirror assuming that a person keeps it 10 cm from his face and views the magnified image of the face at the closest comfortable distance of 25 cm. The radius of curvature of the mirror would then be :

  • Option 1)

    30 cm

  • Option 2)

    24 cm

  • Option 3)

    60 cm

  • Option 4)

    -24 cm

 

Answers (1)

best_answer

As we learnt in

Mirror Formula -

\frac{1}{v}+\frac{1}{u}=\frac{1}{f}


 

- wherein

u= Object distance from pole of mirror.

v= Image distance from pole of mirror.

f= focal length of the mirror.

 

 

Relation between focal length and radius of curvature -

f=\frac{R}{2}

 

- wherein

R = Radius of curvature

This is valid only for smaller angle of incidence.

i.e.paraxial rays

 

 From question v = 15 cm,  u = -10 cm

Radius of curvature R = 2f = ?

Mirror formula \frac{1}{v}+\frac{1}{u}=\frac{1}{f}=\frac{1}{15}+\frac{1}{(-10)}=\frac{1}{f}

 f = - 30 cm

\therefore    R= 2(-30) = - 60 cm 

Correct option is 3.

 

 

 

 


Option 1)

30 cm

This is an incorrect option.

Option 2)

24 cm

This is an incorrect option.

Option 3)

60 cm

This is the correct option.

Option 4)

-24 cm

This is an incorrect option.

Posted by

Plabita

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE

Similar Questions

Trending Articles/News

anam-khan

BTech Admission 2025 Live: JEE Mains, SRMJEEE, MET registrations underway; MHT CET syllabus updates
anam-khan

Centre issues coaching guidelines, prohibits centres from using false claims like '100% selection'
anam-khan

BTech Admissions 2025 Live: JEE Mains, SRMJEE, VITEEE dates out; AEEE, MET registrations underway

Latest Question