A) 6 cm
B) 12 cm
C) 24 cm
D) 30 cm
Correct Answer: A
Solution :
\[\frac{{{f}_{l}}}{{{f}_{a}}}=\frac{{{(}_{a}}{{\mu }_{g}}-1)}{{{(}_{l}}{{\mu }_{g}}-1)}=\] \[\frac{\left( \frac{3}{2}-1 \right)}{\left( \frac{3/2}{5/4}-1 \right)}=\frac{5}{2}\] \[\therefore \] \[{{f}_{l}}={{f}_{a}}\left( \frac{5}{2} \right)=\frac{12\times 5}{2}=30\]\[cm\]You need to login to perform this action.
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