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Answer the following questions : (a) You have learnt that plane and convex mirrors produce virtual images of objects. Can they produce real images under some circumstances ? Explain. (b) A virtual image, we always say, cannot be caught on a screen. Yet when we 'see' a virtual image, we are obviously bringing it on to the 'screen' (i.e., the retina) of our eye. Is there a contradiction ? (c) A diver under water, looks obliquely at a fisherman standing on the bank of a lake. Would the fisherman look taller or shorter to the diver than what he actually is ? (d) Does the apparent depth of a tank of water change if viewed obliquely ? If so, does the apparent depth increase or decrease ? (e) The refractive index of diamond is much greater than that of ordinary glass. Is this fact of some use to a diamond cutter ? |
| Answer» <html><body><p></p>Solution :(a) We know that both plane and convex mirrors produce virtual images of real objects. They may produce real image of virtual objects i.e., when the incident light beam is highly convergent, converging towards a point O behind the mirror as shown in Fig. 9.05(a) for a plane mirror and Fig. 9.05(b) for a convex mirror respectively.<br/> <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/U_LIK_SP_PHY_XII_C09_E01_018_S01.png" width="80%"/> <br/> (b) A virtual image <a href="https://interviewquestions.tuteehub.com/tag/means-1091780" style="font-weight:bold;" target="_blank" title="Click to know more about MEANS">MEANS</a> that the reflected/ refracted light rays form a divergent beam and <a href="https://interviewquestions.tuteehub.com/tag/hence-484344" style="font-weight:bold;" target="_blank" title="Click to know more about HENCE">HENCE</a> it cannot be converged on a screen. However, when we .see. a virtual image, this virtual image acts as an object and the convex lens of eye converges it on the screen (the retina) of our eye. Therefore, there is no <a href="https://interviewquestions.tuteehub.com/tag/contradiction-425534" style="font-weight:bold;" target="_blank" title="Click to know more about CONTRADICTION">CONTRADICTION</a> of any sort. <br/> (c) As shown in Fig. 9.06, when an object OO. situated in air is viewed from inside water its virtual, erect and magnified image II. is formed. It is on this account that to a diver under water a fisherman standing on the bank of lake appears to be taller than what he actually is.<br/> <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/U_LIK_SP_PHY_XII_C09_E01_018_S02.png" width="80%"/> <br/> (d) The apparent depth decreases when a tank filled with water is viewed obliquely compared to the depth when <a href="https://interviewquestions.tuteehub.com/tag/seen-3017120" style="font-weight:bold;" target="_blank" title="Click to know more about SEEN">SEEN</a> near normally. <br/> (e) Refractive index of diamond is much greater than that of glass. In fact, it is 2.42 as compared to 1.5 of glass. Consequently, <a href="https://interviewquestions.tuteehub.com/tag/critical-427694" style="font-weight:bold;" target="_blank" title="Click to know more about CRITICAL">CRITICAL</a> angle for diamond air interface is quite small (about 24°). Thus, a skilled diamond cutter has a large option to cut the diamond faces for any value of angle of incidence varying from 24° to 90°. It makes his work easy.</body></html> | |