Physics: Light, Reflection, and Refraction
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Questions and Answers

Why does the sun appear white at noon?

  • The atmosphere scatters all colors of light equally at noon. (correct)
  • Red light is scattered the least at noon.
  • Blue light is scattered the least at noon.
  • The sun emits mostly white light at noon.

    • Which phenomenon is responsible for the twinkling of stars?

  • Dispersion of light by water droplets in the atmosphere.
  • Refraction of light by layers of air with varying densities. (correct)
  • Diffraction of light by dust particles in the atmosphere.
  • Reflection of light by clouds.

    • What is the main reason the sky appears blue?

  • The atmosphere scatters red and orange light more strongly than other colors.
  • The atmosphere scatters violet and blue light more strongly than other colors. (correct)
  • The atmosphere absorbs ultraviolet radiation more strongly than other colors.
  • The atmosphere absorbs blue light more strongly than other colors.

    • Why are danger signals on tall buildings often red?

    <p>Red light is scattered the least by smoke and fog, ensuring visibility even in hazy conditions.</p> Signup and view all the answers

    Which of the following statements about the scattering of light is TRUE?

    <p>Shorter wavelengths of light are scattered more than longer wavelengths.</p> Signup and view all the answers

    Which of the following scenarios would result in the LEAST amount of light scattering?

    <p>Sunlight passing through a clear, dry atmosphere.</p> Signup and view all the answers

    Which of the following is NOT a factor that influences the scattering of light?

    <p>The temperature of the surrounding environment.</p> Signup and view all the answers

    Which of the following colors of light is scattered the LEAST by the atmosphere?

    <p>Red.</p> Signup and view all the answers

    Which of the following statements BEST describes the relationship between the color of the sky and the scattering of light?

    <p>The sky appears blue because the atmosphere scatters blue light more strongly than other colors.</p> Signup and view all the answers

    If the atmosphere were to completely absorb all colors of light, what color would the sky appear?

    <p>Black.</p> Signup and view all the answers

    Study Notes

    Light, Reflection, and Refraction

    • A concave mirror of focal length 20 cm will produce a real and inverted image with a magnification of -2 if the object is at a distance of 30 cm from the pole.
    • The focal length of a plane mirror is infinity.
    • A concave spherical mirror of radius of curvature 120 cm will produce an erect image four times the natural size if the object is at a distance of 240 cm from the mirror.
    • When a light ray enters from medium A to medium B, the refractive index of medium B relative to A is greater than unity.
    • A 2cm pin placed 10 cm in front of a concave mirror of focal length 10 cm will produce an erect image 4 cm in height.

    Mirrors and Lenses

    • A concave mirror has a centre of curvature, pole, and focus, whereas a convex lens has a principal axis, focus, and radius of curvature.
    • A concave lens having 4 dioptre power has a focal length 0.25 m, whereas a concave lens having -4 diopter power has a focal length -0.25 m.
    • When a ray of light travels from a rarer medium to a denser medium, it bends towards the normal.
    • The path of a ray of light passing through a rectangular glass slab is traced by drawing a straight line.

    Lenses and Image Formation

    • A convex lens of focal point 15 cm has a power of 6.67 D.
    • A combination of a convex lens of power +3.5 D and a concave lens of power -2.5 D will behave like a convergent lens of focal length 200 cm.
    • A device X that forms an image of a distant object on a white screen at a distance of 30 cm is a convex lens of focal length 15 cm.
    • A convex lens forms a virtual image of an object placed at a distance of 20 cm, and the focal length of the lens must be greater than 20 cm and less than infinity.

    Refraction and Dispersion

    • When a ray of light passes from air into a denser medium, it deviates towards the normal.
    • A glass slab placed over a page with printed letters will raise the image of the letters, with the letter V raised the most.
    • A rainbow is caused by the dispersion of sunlight from water drops.
    • When sunlight enters a glass prism, it is deviated and dispersed.
    • The clear sky appears blue because blue light is scattered more than other colours by the atmosphere.

    Optical Instruments and Defects

    • A person who cannot see objects beyond 2 m can be corrected using a lens of power -0.5 D.
    • Twinkling of stars is due to the refraction of light by different layers of the atmosphere with varying refractive indices.
    • The danger signals installed at the top of tall buildings are red in colour because red light is scattered the least by smoke or fog.

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    Holiday HW Phy PDF

    Description

    Test your understanding of light reflection, refraction, and image formation with concave and plane mirrors. Learn about focal lengths, magnification, and refractive indices.

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