AP and TS EAMCET Engineering Model Paper 1

A ray of light starting from O gets refracted twice. The ray of light is travelling in a direction from left to right. Hence, the distance measured in this direction are taken positive.Applying

µ2

v

−

µ1

u

=

µ2−µ1

R

, twice with proper signs.
We have,

3 2

v

−

4 3

−20

=

3 2 − 4 3

10

Or v=−30cm
Now, the first image I1 acts as an object for the second surface, where
BI1=u=−(30+20)=−50cm

4 3

v

−

3 2

−50

=

4 3 − 3 2

−10

∴v1=−100cm, i.e., the final image I3 is virtual and is formed at a distance of 100 cm(towards left) from B.