IIT JEE , AIEEE Forum - Physics , Optics

keertypraveena

PLZ ANSWER WITH ELABORATE EXPLANATION

1. a ray of light incident on a slab of transparent material is partly refracted into the slab.the reflected and refracted rays are perpendicular.angle of incidence is "i".the refractive index is?????

2.an air bubble is inside water the ref.ind of water is 4/3.at what distance from bubble should a point object be placed so as to form real image at same distance from bubble.??????

3.a point source of light at the surface of a sphere causes a parallel beam of light to emerge from the opp surface of sphere.the ref index of the material of the sphere is.???????

vikramdpatil

1] n = tan i
i=angle of reflection
angle of reflection =refraction r
r=180-(90 +i)=90-i
n=sini/sinr=sini/cosi=tani..

vikramdpatil

correction...
angle of incidence=angle of refraction

iitkgp_bipin

Let i be the angle of incidence.

If you will draw a ray diagram you will find the angle of refraction to be 90-i since refracted ray and reflected ray are perpendicular.

Apply Snell's law : sini = nsin(90-i)

sini = n.cosi

n = tani

keertypraveena

but options are tan inverse i,sin inverse i,cot inverse i,cos inversei
sso do you say options are wrong
ok ans next questions plzzzzzzz
i will rate
answers are:1.tan inverse i

2.the air bubble cannot form real image

3.2

keertypraveena

plz answer for other questions also
plzzzzzzzzzzzzz

caprio.nups

for ur second ques the ray will go from denser to rarer medium...as refractive index of air is one n of water is greater then one...and also the when the ray will pass it will travel as in case of concave surface..so only virtual image cn b formed...n no real images cn b formed..

arp

Hi praveen,

for question 1 .. refractive index is tani.
Expalnatyion : It can't be tan inverse I at all. it has to be a number which is tani not taninverse i

for question 2 .. yes it acts as concave lens.. since [n(air) - n(water)] is negative and hence no convergence of rays at all.

for question 3 ..n=2

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