Ray Optics · JEE Main previous year questions

2014 2 questions

1. Q512014 · 6 Apr 2014 · Shift 1

   A thin convex lens made from crown glass ($\mu =\frac{3}{2}$) has focal length $f$. When it is measured in two different liquids having refractive indices $\frac{4}{3}$ and $\frac{5}{3}$, it has the focal lengths $f_1$ and $f_2$ respectively. The correct relation between the focal lengths is :

   1. A.$f_1=f_2<f$
   2. B.$f_1>f$ and $f_2$ becomes negative
   3. C.$f_2>f$ and $f_1$ becomes negative
   4. D.$f_1$ and $f_2$ both become negative
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   Answer: B

2. Q522014 · 6 Apr 2014 · Shift 1

   A green light is incident from the water to the air - water interface at the critical angle ($\theta$). Select the correct statement.

   1. A.The entire spectrum of visible light will come out of the water at an angle of $90^{\circ }$ to the normal.
   2. B.The spectrum of visible light whose frequency is less than that of green light will come out to the air medium.
   3. C.The spectrum of visible light whose frequency is more than that of green light will come out to the air medium.
   4. D.The entire spectrum of visible light will come out of the water at various angles to the normal.
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   Answer: B