Total Internal Reflection - NEET Physics Questions
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Total Internal Reflection

Question 1: moderate

A ray of light from a denser medium strikes a rarer medium at an angle of incidence i. If the reflected and refracted rays are mutually perpendicular to each other then what is the value of critical angle ?

1. \[sin^{-}(tani)\]
2. \[cos^{-}(tani)\]
3. \[sin^{-}(coti)\]
4. None of these
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Question 2: difficult

As shown in figure light P enters to slab at an angle 60° with normal and inside slab Q makes total internal reflection. Find minimum refractive index of slab.

1. 1.72
2. 1.52
3. 1.32
4. 1.12
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Question 3: moderate

The speed of light in media M1 and M2 is \[1.5\times 10^{8} m/s and 2.0\times 10^{8}\] respectively. A ray of light enters from medium M1 to M2 at an incidence angle i. If the ray suffers total internal reflection, the value of i is :

1. Equal to or less than sin–¹(3/5)
2. Equal to or greater than sin–¹(3/4)
3. Less than sin–¹(2/3)
4. Equal to sin–¹(2/3)
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Question 4: easy

If the critical angle for total internal reflection from a medium to vacuum is 30°, the velocity of light in the medium is

1. \[3\times 10^{8} m/s \]
2. \[1.5\times 10^{8} m/s \]
3. \[6\times 10^{8} m/s \]
4. \[\sqrt{3}\times 10^{8} m/s \]
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Question 5: moderate

A transparent solid cylindrical rod has a refractive index of 2/√3. It is surrounded by air. A light ray is incident at the mid-point of one end of the rod as shown in the figure.

The incident angle θ for which the light ray grazes along the wall of the rod is

1. \[sin^{-1}(1/2)\]
2. \[sin^{-1}(\sqrt{3}/2)\]
3. \[sin^{-1}({2}/\sqrt{3})\]
4. \[sin^{-1}({1}/\sqrt{3})\]
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Question 6: moderate

A point source of light is kept at a depth of h in water of refractive index 4/3. The radius of the circle at the surface of water through which light emits is

1. \[\frac{3}{\sqrt{7}}h\]
2. \[\frac{\sqrt{7}}{3}h\]
3. \[\frac{\sqrt{3}}{7}h\]
4. \[\frac{7}{\sqrt{3}}h\]
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Question 7: difficult

Figure shows a mixture of blue, green and red coloured rays incident normally on a right angled prism. The critical angles of the material of the prism for red, green and blue are 46°, 44° and 43° respectively. The arrangement will separate.

1. Green colour from red and blue
2. All the three colurs
3. Red colour from blue and green
4. Blue colour from red and green
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Question 8: difficult

A light ray travelling in a glass medium is incident on glass-air interface at an angle of incidence q. The reflected (R) and transmitted (T) intensities, both as function of q, are plotted. The correct figure is : (θc = critical angle)

1.
2.
3.
4.
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Question 9: moderate

A small coin is resting on the bottom of a beaker filled with liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface. How fast is the light travelling in the liquid ?

1. \[2.4\times 10^{8}m/s\]
2. \[3.0\times 10^{8}m/s\]
3. \[1.2\times 10^{8}m/s\]
4. \[1.8\times 10^{8}m/s\]
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