Question

How to find the critical angle of glass in respect to air and critical angle of air in respecr to glass?

Answer 1

As you know critical angle is the angle above which refraction of light rays travelling from denser to rarer does not takes place.
So use the snell's law:
                                m.sin i=n.sin r
                                 where m=R.I of denser medium(glass)=4/3
                                            n=R.I of rarer medium(air)=1
                                            i= angle of incidence in denser medium(glass) 
                                            r=angle of refraction in rarer medium(air)
          For critical angle,r=90 degree
Just put the values in the equation and you will get the "critical angle of glass with respect to air" .
Now you asked about critical angle of air with respect to glass....well I never heard of this...because just see the definition of critical angle.There is a condition that light rays travel from denser to rarer.Then how can you measure the "critical angle of air with respect to glass" when it does not exist.....

Now this is my knowledge....if it exist(I am 100% sure that it does not)....then it is the reciprocal of the critical angle of glass with respect to air"...... 

I AM SAYING AGAIN....IT DOES NOT EXIST....I recommend that you ask your teacher about it's existance....if exist...then the above is correct....I am repeating ....if only if it exist .

SO PLZ RATE IT....AND IF POSSIBLE PLZ MARK AS BRAINLEST