​Please explainn the second point of question 3. What is critical angle ......?​

​Please explainn the second point of question 3. What is critical angle ......?​ of a •s retracte•d gum. V4hch S •s optically •e other? two poults of obrc-t ooå-3? figure gives t• by the object ttvm the change length a - out the factors on which refractive ot a medium depends. index of a medium depends on : the nature of the medium the colour or wavelength of the incident light. 3. under what conditions there won't be any refraction of light, when it enters from one medium to another? are following two possible cases: (j When light is incident at 900 (normal) it will not It is only applicable when light passes from optical denrr medium to rarer medium. If a light ray is incident at an angle greater than critical angle, it will reflect and not refract. 4. Aray of light travelling in air is incident on a rectangular glass slab. What will happen? A ray light passing through a rectangular glass slab un&rgoes two refractions and it emerges from opBhite side of the slab in a direction parallel to the duection of incident light. The emergent ray is sol. of a lay of as below: thickness of displacement angle of incidence. A student is stanc room. He wants to of him on d wal smallest lenqth of sol. 7. so as to enable hil back wall? In order to see the f student should take t to be half the height Observe the diagram ot an 01 is formed after lens. 26