1. Opaque materials (do not allow light to pass through): 1. Piece of rock 2. Sheet of aluminium 3. Mirror 4. Wooden board 5. CD 6. Piece of red hot iron 7. Umbrella 8. Wall 9. Sheet of carbon paper 10. Sheet of cardboard 11. Wire mesh 12. Kerosene stove Transparent materials (allow light to pass throuRead more

    Opaque materials (do not allow light to pass through):
    1. Piece of rock
    2. Sheet of aluminium
    3. Mirror
    4. Wooden board
    5. CD
    6. Piece of red hot iron
    7. Umbrella
    8. Wall
    9. Sheet of carbon paper
    10. Sheet of cardboard
    11. Wire mesh
    12. Kerosene stove

    Transparent materials (allow light to pass through clearly):
    1. Air
    2. Water
    3. Sheet of plain glass

    Translucent materials (allow some light but not a clear view):
    1. Sheet of polythene
    2. Smoke
    3. Fog
    4. Sheet of cellophane

    Luminous materials (emit light):
    1. Flame of a gas burner
    2. Lighted fluorescent tube
    3. Lighted torch
    4. Sun
    5. Firefly

    Non-luminous materials (do not emit light):
    1. All materials except those listed as luminous

    This classification helps understand which materials allow light to pass through, whether they emit light, and the distinction between opaque, transparent, and translucent materials.

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  2. A cylinder with a circular cross-section, when held upright, casts a circular shadow. When turned 90 degrees with its circular side perpendicular to the ground, it produces a rectangular shadow. The change in orientation causes the shape of the shadow to shift from circular to rectangular.

    A cylinder with a circular cross-section, when held upright, casts a circular shadow. When turned 90 degrees with its circular side perpendicular to the ground, it produces a rectangular shadow. The change in orientation causes the shape of the shadow to shift from circular to rectangular.

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  3. No, in a completely dark room, if you hold up a mirror in front of you, you won't see a reflection of yourself. A mirror reflects light, and in a completely dark room, there is no light available to illuminate your image. For a mirror to reflect an image, it requires light to fall on the object beinRead more

    No, in a completely dark room, if you hold up a mirror in front of you, you won’t see a reflection of yourself. A mirror reflects light, and in a completely dark room, there is no light available to illuminate your image. For a mirror to reflect an image, it requires light to fall on the object being reflected. Without any light, there won’t be any reflection visible in the mirror.

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  4. An electric switch manages the flow of electricity in devices. Gadgets like lamps, TVs, fans, computers, toasters, microwaves, kettles, hairdryers, vacuums, and washing machines use switches. They allow users to turn these devices on or off, controlling their functionality and power consumption convRead more

    An electric switch manages the flow of electricity in devices. Gadgets like lamps, TVs, fans, computers, toasters, microwaves, kettles, hairdryers, vacuums, and washing machines use switches. They allow users to turn these devices on or off, controlling their functionality and power consumption conveniently.

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  5. If the conduction tester's bulb glows, the object is a conductor. Conductors allow electricity to flow through them. The glowing bulb indicates that the tested object permits the passage of electric current, distinguishing it from insulators, which do not conduct electricity and would not light up tRead more

    If the conduction tester’s bulb glows, the object is a conductor. Conductors allow electricity to flow through them. The glowing bulb indicates that the tested object permits the passage of electric current, distinguishing it from insulators, which do not conduct electricity and would not light up the bulb.

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