Question

14. An object is placed 12 cm from a concave mirror which forms its real
image at a distance 18 cm. calculate the focal length of the mirror. (2)
15. Light travel from rarer medium 1 to a denser medium 2 The angle of
incidence and refraction are respectively 600 and 30°. Calculate the refractive
index of second medium with respect to the first medium​

Answer 1

Object distance =12cm

h  

i

​  

=2h  

0

​  

 

h  

i

​  

= height of image

h  

o

​  

= height of object

Magnification, m=  

h  

0

​  

 

h  

i

​  

 

​  

 

=  

h  

0

​  

 

−2h  

0

​  

 

​  

 

m=−2

We know,

m=−  

u

v

​  

 

−2=  

(−12)

−v

​  

 

v=−24cm