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A thin lens made of glass (refractive index = 1.5) of focal length f= 16 cm is immersed in a liquid of refractive index 1.42. If its focal length in liquid is f_1, then the ratio f_1lf is closest to the integer |
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Answer» 9 `(1)/(f_a)=((mu_g)/(mu_a)-1)[(1)/(R_1)-(1)/(R_2)]` In liquid medium, `(1)/(f_L)=((mu_g)/(mu_L)-1)((1)/(R_1)=(1)/(R_2))` `therefore(f_a)/(f_L)=((mu_g)/(mu_L)-1)/((mu_g)/(mu_a)-1)=(mu_g-mu_L)/(mu_g-mu_a)xx(mu_a)/(mu_L)` `=(1.5-1.42)/(1.5-1.0)xx(1)/(1.42)` `=(0.08)/(0.5)xx(1)/(1.42)` `therefore(f_L)/(f_a)=(0.71)/(0.08)` `=8.875~~9` |
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