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Geometrical optics
6 Class 10 Physics questions with answers and explanations.
Printable worksheet with answer key
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The speed of light in vacuum is about:
- 1 3 x 10^6 m/s
- 2 3 x 10^10 m/s
- 3 340 m/s
- 4 3 x 10^8 m/s
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Correct answer: 3 x 10^8 m/s
Light travels at about 3 x 10^8 m/s in vacuum.
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A concave mirror is also called a:
- 1 Prism
- 2 Plane mirror
- 3 Converging mirror
- 4 Diverging mirror
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Correct answer: Converging mirror
A concave mirror converges parallel rays to a focus.
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The focal length of a mirror of radius of curvature 20 cm is:
- 1 40 cm
- 2 10 cm
- 3 20 cm
- 4 5 cm
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Total internal reflection occurs when light goes from:
- 1 Rare to dense medium
- 2 Dense to rare medium above the critical angle
- 3 Air to vacuum
- 4 Any medium at 0 degrees
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Correct answer: Dense to rare medium above the critical angle
It needs light travelling from a denser to a rarer medium with an angle of incidence above the critical angle.
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A convex lens is used to correct:
- 1 Long sight
- 2 Astigmatism only
- 3 Short sight
- 4 Colour blindness
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Correct answer: Long sight
Long sight (hypermetropia) is corrected by a converging, convex lens.
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The power of a lens of focal length 0.5 m is:
- 1 0.5 D
- 2 2 D
- 3 1 D
- 4 5 D