# The reddish appearance of the sun at sunrise and sunset is due to: 1. the scattering of light. 2. the polarisation of light. 3. the colour of the sun. 4. the colour of the sky.

Subtopic:  Total Internal Reflection |
89%
From NCERT
NEET - 2013
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Two plane mirrors are inclined at $$70^\circ.$$ A ray incident on one mirror at an angle, $$\theta$$ after reflection falls on the second mirror and is reflected from there parallel to the first mirror. The value of $$\theta$$ is:
1. $$45^\circ$$
2. $$30^\circ$$
3. $$55^\circ$$
4. $$50^\circ$$
Subtopic:  Reflection at Plane Surface |
54%
From NCERT
NEET - 2013
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A ray of light is incident on a $$60^\circ$$ prism at the minimum deviation position. The angle of refraction at the first face (i.e. incident face) of the prism is:
1. $$30^\circ$$
2. $$45^\circ$$
3. $$60^\circ$$
4. zero

Subtopic:  Prisms |
73%
From NCERT
AIPMT - 2010
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The speed of light in media $$M_1$$ and $$M_2$$ is $$1.5\times10^{8}$$ m/s and $$2.0\times10^{8}$$ m/s respectively. A ray of light enters from medium $$M_1$$ and $$M_2$$ at an incidence angle $$i.$$ If the ray suffers total internal reflection, the value of $$i$$ is:

 1 equal to or less than $$\text{sin}^{-1}\left (\frac{3}{5} \right )$$ 2 equal to or greater than $$\text{sin}^{-1}\left (\frac{3}{4} \right )$$ 3 less than $$\text{sin}^{-1}\left (\frac{2}{3} \right )$$ 4 equal to $$\text{sin}^{-1}\left (\frac{2}{3} \right )$$

Subtopic:  Total Internal Reflection |
89%
From NCERT
AIPMT - 2010
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A converging beam of rays is incident on a diverging lens. Having passed through the lens the rays intersect at a point $$15~\text{cm}$$ from the lens on the opposite side. If the lens is removed the point where the rays meet will move $$5~\text{cm}$$ closer to the lens. The focal length of the lens is:
1.  $$5~\text{cm}$$
2. $$-10~\text{cm}$$
3. $$20~\text{cm}$$
4. $$-30~\text{cm}$$

Subtopic:  Lenses |
53%
From NCERT
AIPMT - 2011
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A thin prism of angle $$15^\circ$$ made of glass of refractive index $$\mu_1=1.5$$ is combined with another prism of the glass of refractive index $$\mu_1=1.75.$$ The combination of the prism produced dispersion without deviation. The angle of the second prism should be:
1. $$5^\circ$$
2. $$7^\circ$$
3. $$10^\circ$$
4. $$12^\circ$$

Subtopic:  Prisms |
82%
From NCERT
AIPMT - 2011
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A rod of length $$10~\text{cm}$$ lies along the principal axis of a concave mirror of focal length $$10~\text{cm}$$ in such a way that its end closer to the pole is $$20~\text{cm}$$ away from the mirror. The length of the image is:
1. $$15~\text{cm}$$
2. $$2.5~\text{cm}$$
3. $$5~\text{cm}$$
4. $$10~\text{cm}$$

Subtopic:  Reflection at Spherical Surface |
67%
From NCERT
AIPMT - 2012
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For the angle of minimum deviation of a prism to be equal to its refracting angle, the prism must be made of a material whose refractive index:

 1 lies between $$2$$ and $$\sqrt{2}$$ 2 is less than $$1$$ 3 is greater than $$2$$ 4 lies between $$\sqrt{2}$$ and $$1$$

Subtopic:  Prisms |
58%
From NCERT
AIPMT - 2012
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A convex lens and a concave lens, each having the same focal length of 25 cm, are put in contact to form a combination of lenses. The power in dioptres of the combination is:

1. 25

2. 50

3. infinite

4. zero

Subtopic:  Lenses |
59%
From NCERT
AIPMT - 2006
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A microscope is focused on a mark on a piece of paper and then a slab of glass of thickness 3 cm and a refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again?

1. 1 cm upward

2. 4.5 cm downward

3. 1 cm downward

4. 2 cm upward

Subtopic:  Simple & Compound Microscope |
54%
From NCERT
AIPMT - 2006
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