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Biology Genius

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  1. Asked: October 20, 2020In: Class 10

    A person needs a lens of power –5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting

    Biology Genius
    Added an answer on December 12, 2020 at 6:55 am

    For distant vision = −0.181 m, for near vision = 0.667 m The power P of a lens of focal length f is given by the relation P = 1/f(in metres) (i) Power of the lens used for correcting distant vision = −5.5 D Focal length of the required lens, f =1/P F = 1/-5.5 = -0.181ₘ The focal length of the lens fRead more

    For distant vision = −0.181 m, for near vision = 0.667 m
    The power P of a lens of focal length f is given by the relation
    P = 1/f(in metres)
    (i) Power of the lens used for correcting distant vision = −5.5 D
    Focal length of the required lens, f =1/P
    F = 1/-5.5 = -0.181ₘ
    The focal length of the lens for correcting distant vision is −0.181 m.
    (ii) Power of the lens used for correcting near vision = +1.5 D
    Focal length of the required lens, f =1/P
    F = 1/1.5 = +0.667ₘ

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/

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  2. Asked: October 20, 2020In: Class 10

    Define 1 dioptre of power of a lens.

    Biology Genius
    Added an answer on December 12, 2020 at 6:39 am

    Power of lens is defined as the reciprocal of its focal length. If P is the power of a lens of focal length F in metres, then P= 1/f(in metres) The S.I. unit of power of a lens is Dioptre. It is denoted by D. 1 dioptre is defined as the power of a lens of focal length 1 metre. 1 D = 1 m−¹ For more aRead more

    Power of lens is defined as the reciprocal of its focal length. If P is the power of a lens of
    focal length F in metres, then
    P= 1/f(in metres)
    The S.I. unit of power of a lens is Dioptre. It is denoted by D.
    1 dioptre is defined as the power of a lens of focal length 1 metre.
    1 D = 1 m−¹

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-10/

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  3. Asked: October 20, 2020In: Class 10

    A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why?

    Biology Genius
    Added an answer on December 12, 2020 at 6:08 am

    The light ray bends towards the normal. When a ray of light travels from an optically rarer medium to an optically denser medium, it gets bent towards the normal. Since water is optically denser than air, a ray of light travelling from air into the water will bend towards the normal. For more answerRead more

    The light ray bends towards the normal.
    When a ray of light travels from an optically rarer medium to an optically denser medium,
    it gets bent towards the normal. Since water is optically denser than air, a ray of light
    travelling from air into the water will bend towards the normal.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-10/

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  4. Asked: October 20, 2020In: Class 10

    A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?

    Biology Genius
    Added an answer on December 12, 2020 at 5:48 am

    Power of a lens, P = 1/f (in meters) Power, P = 1.5d F = 1/1.5 = 10/15 = 0.66m A convex lens has a positive focal length. Hence, it is a convex lens or a converging lens. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-10/

    Power of a lens, P = 1/f (in meters)
    Power, P = 1.5d
    F = 1/1.5 = 10/15 = 0.66m
    A convex lens has a positive focal length. Hence, it is a convex lens or a converging lens.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-10/

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  5. Asked: October 20, 2020In: Class 10

    Find the focal length of a lens of power – 2.0 D. What type of lens is this?

    Biology Genius
    Added an answer on December 12, 2020 at 5:44 am

    Power of a lens, P = 1/f (in meters) P = -2 D f = -1/2 = -0.5m A concave lens has a negative focal length. Hence, it is a concave lens. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-10/

    Power of a lens, P = 1/f (in meters)
    P = -2 D
    f = -1/2 = -0.5m
    A concave lens has a negative focal length. Hence, it is a concave lens.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-10/

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