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Science Assertion & Reason

Light. · Tamil Nadu Board STD 8 (Tamil - English Medium). 4 questions.

Questions

Assertion & Reason

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4 questions · timed · auto-graded

MCQ 11 Mark
Assertion : We can see the rainbow in the sky when the rain starts falling after a spell of bright sunlight.
Reason : The rainbow is formed due to the dispersion of light.
  • A
    Both assertion and reason are true and the reason is the correct explanation of the assertion.
  • B
    Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
  • C
    The assertion is true, but the reason is false.
  • ✓
    The assertion is false, but the reason is true.
Answer
Correct option: D.
The assertion is false, but the reason is true.
The assertion is false, but the reason is true
Correct explanation:
The rainbow is formed when the light passes through the water droplets in air after it rains and gets dispersed into seven colours.
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MCQ 21 Mark
Assertion : The mirrors used in search lights are parabolic and not concave spherical.
Reason : In concave spherical mirror the image formed is always virtual.
  • A
    Both assertion and reason are true and the reason is the correct explanation of the assertion.
  • B
    Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
  • ✓
    The assertion is true, but the reason is false.
  • D
    The assertion is false, but the reason is true.
Answer
Correct option: C.
The assertion is true, but the reason is false.
The assertion is true, but the reason is false
Correct explanation:
In search lights, we need an intense parallel beam of light. If a source is placed at the focus of a concave spherical mirror only paraxial rays are rendered parallel. Due to large aperture of mirror, marginal rays give a divergent beam. But in case of parabolic mirror, when source is at the focus, beam of light produced over the entire cross – section of the mirror is a parallel beam.
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MCQ 31 Mark
Assertion : Convex mirrors are used as rear view mirror in vehicles for observing traffic at our back.
Reason : A convex mirror has a much larger field of view.
  • ✓
    Both assertion and reason are true and the reason is the correct explanation of the assertion.
  • B
    Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
  • C
    The assertion is true, but the reason is false.
  • D
    The assertion is false, but the reason is true.
Answer
Correct option: A.
Both assertion and reason are true and the reason is the correct explanation of the assertion.
Both assertion and reason are true and the reason is the correct explanation of the assertion
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MCQ 41 Mark
Assertion : A ray incident along normal to the mirror retraces its path
Reason : In reflection, angle of incidence is always equal to angle of reflection.
  • ✓
    Both assertion and reason are true and the reason is the correct explanation of the assertion.
  • B
    Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
  • C
    The assertion is true, but the reason is false.
  • D
    The assertion is false, but the reason is true.
Answer
Correct option: A.
Both assertion and reason are true and the reason is the correct explanation of the assertion.
Both assertion and reason are true and the reason is the correct explanation of the assertion
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Assertion & Reason - Science STD 8 Questions - Vidyadip