Question

To the fish, how far away does the watcher appear to be?

$d_1=8cm$

$d_2=3cm$

$d_3=6.8cm$

• A. $\text{20 cm}$
• B. $\text{10 cm}$
• C. $\text{30 cm}$
• D. $\text{40 cm}$

Answer 1

The correct option is A $\text{20 cm}$

$\begin{array}{c}\text{As we are considering fish's sight}\\ \text{6.8}cm\text{that is direct water distance will be simply added , but for glass we will have to find}\end{array}$

$\mu \left(\frac{n_1}{n_2}\right)$

By using the formula

$\Rightarrow 8\times \left(\frac{n_1}{n_2}\right)+3\left(\frac{n_1}{n_2}\right)+6.8$

$\begin{array}{cc}\Rightarrow & 8\left(\frac{4}{3}\right)+3\left(\frac{4/3}{8/5}\right)+6.8\\ \Rightarrow & \frac{79}{6}+6.8=13.16+6.8=19.96\approx 20\left(\text{approx}\right)\end{array}$

Hence option (A) is corrrect