Ray Optics And Optical Instruments Ques 12
12. An air bubble in a glass slab $(\mu=1.5)$ is $5$ $ cm$ deep when viewed from one face and $2 $ $cm$ deep when viewed from the opposite face. The thickness of the slab is
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(a) $7.5 $ $cm$
(b) $10.5 $ $cm$
(c) $7 $ $cm$
(d) $10 $ $cm$
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Answer:
Correct Answer: 12.(b)
Solution:
- (b) $1.5=\frac{\text{ Real depth }(R_1)}{\text{ Apparent depth }(5 cm)}$
$\therefore R_1=1.5 \times 5=7.5 $ $cm$
For opposite face,
$1.5=\frac{R_2}{2} \Rightarrow R_2=3.0$ $ cm$
$\therefore$ Thickness of the slab $=R_1+R_2$
$ =7.5+3=10.5 $ $cm $
If object and observer are situated in different medium then due to refraction, object appears to be displaced
Refractive index, $\mu=\frac{\text{ Real depth }(h)}{\text{Apparent depth}(h^{\prime})}$
Real depth > Apparent depth
In case object is in rarer medium and object is in denser medium then, $\mu=\frac{h^{\prime}}{h}$
Real depth < apparent depth
BETA
