Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • Engineering
  • An object is at a distance of 10 cm from a mirror and the image of the object is at a distance of 30 cm from the mirror on the same side as the object. Then nature of the mirror and its focal lengt

An object is at a distance of 10 cm from a mirror and the image of the object is at a distance of 30 cm from the mirror on the same side as the object. Then nature of the mirror and its focal length is:

Option: 1

Convex, 15cm


Option: 2

Concave, 1.5cm


Option: 3

Convex, 7.5cm


Option: 4

Concave, 7.5cm


Answers (1)

best_answer

As we learn

Sign Convention -

 

1)    All distance are measured from pole.

2)    Distance measured in the direction of incident rays are taken as positive.

3)     Distance measured in the direction opposite to that of incident rays are taken as negative.

4)    Distance above the principal axis as positive and below the principal axis as negative.

u = -10 cm 

v = - 30cm  from sign convention

from mirror formula

\frac{1}{f}=\frac{1}{v}+\frac{1}{u} = -\frac{1}{30}-\frac{1}{10}=\frac{-4}{30}

f = -7.5 cm

since focal length is negative hence its mirror concave

 

 

 

Posted by

Nehul

View full answer

Similar Questions

Latest Question