Question

solve question no. 10 n 15 plzz

Answer 1

for minimum deviation ,

angle of incidence = angle of emergent
and
angle of refraction at surface of incident = incident angle for emergent surface =∅


angle of incidence = 60° = angle of emergent
let refractive index of prism = u

then ,

for fist face
——————

1 x sin60° = u sin∅
where ∅ is angle of refraction in 1st face

now, in 2nd face
--------------------------
usin∅ = 1x sin60°

but we know, refractive index is required
so, some data missing here
if u = given
then you easily find out
∅ = ??


15 )

information given
==================
i = angle of incidence
90° = angle of emergence
u = refractive index of prism
A = angle of prism

in first face

1 x sini = u sinr1

because , i is small
so, sini = i
sinr1 =r1
sinr2 =r2

so, i = ur1 ---------(1)

in 2nd face

usinr2 = 1 x sin90

u sinr2 = 1
ur2 = 1 ----------(1)

equation (1) and (2)

r1/r2 = i

r1 = ir2

we know,
A = r1 + r2
A =r1 +ir1
A =(1+i)r1
from equation (1)

A =(1 + i)i/u

uA =i + i²

we know,
i is small so, i² is also very small

i >>i²


so, i² can be neglected

uA = i

option (3) is correct