KVPY Sample Paper KVPY Stream-SX Model Paper-13

  • question_answer
    Diameter of a planoconvex lens of focal length 37 cm is 6 cm. It's thickness at the centre is 5 mm. The speed of light in the material of the lens is -

    A) \[{{10}^{8}}m/s\]

    B) \[2.4\times {{10}^{8}}m/s\]

    C) \[12\times {{10}^{8}}m/s\]      

    D) \[3\times \text{1}{{\text{0}}^{\text{8}}}m/s\]

    Correct Answer: B

    Solution :

    \[\frac{1}{37}=(\mu -1)\left( \frac{1}{\infty }+\frac{1}{R} \right)\]
    \[\Rightarrow \mu =1.25=\frac{c}{v}\]
    \[v=\frac{3\times {{10}^{8}}}{1.25}=2.4\times {{10}^{8}}m/s\]

You need to login to perform this action.
You will be redirected in 3 sec spinner