Class 7 Science Exam-concept Based

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| By Manickaraj20
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Manickaraj20
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Quizzes Created: 1 | Total Attempts: 640
Questions: 16 | Attempts: 640

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Class 7 Science Exam-concept Based - Quiz

The class 7 Science exams quiz below tests on some basic light concepts studied in 7th grade. How good are you with this topic? The simplicity of the question structures makes it easy. All the best.


Questions and Answers
  • 1. 

    A polarizing filter is designed to  __________________

    Explanation
    A polarizing filter is designed to block out certain angles of light waves, allowing only light waves that are aligned in a specific direction to pass through. This filtering process helps to reduce glare and unwanted reflections, resulting in improved clarity and contrast in photographs or videos. By blocking out certain angles of light, the polarizing filter enhances color saturation and reduces atmospheric haze, making it a valuable tool for photographers and videographers in various lighting conditions.

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  • 2. 

    A packet, or bundle of light energy is called a(n) __________________

    Explanation
    A packet, or bundle of light energy is called a photon. Photons are elementary particles that carry electromagnetic radiation, including visible light. They have zero mass and travel at the speed of light. Photons are the basic units of all forms of electromagnetic radiation and are responsible for transmitting energy and information in the form of light.

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  • 3. 

    The band of colours visible in a rainbow is called:

    Explanation
    The band of colors visible in a rainbow is called the visible spectrum. The visible spectrum refers to the range of electromagnetic radiation that is visible to the human eye, which includes colors ranging from red to violet. When sunlight is refracted and reflected by water droplets in the atmosphere, it creates a rainbow, which displays the full range of colors in the visible spectrum.

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  • 4. 

    The first part of photosynthesis is known as:

    Explanation
    The first part of photosynthesis is known as light reactions. During this process, light energy is absorbed by chlorophyll molecules in the chloroplasts of plant cells. This energy is then converted into chemical energy in the form of ATP and NADPH. These energy-rich molecules are used in the second part of photosynthesis, known as the Calvin cycle, to produce glucose and other organic compounds. Light reactions are essential for capturing and converting light energy into a usable form for the plant.

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  • 5. 

    Light from a candle is not visible when it is seen through a narrow bent tube, because

    Explanation
    When light travels through a narrow bent tube, it undergoes multiple reflections and scattering. As a result, the light rays become dispersed and lose their intensity. This dispersion and loss of intensity make the light from the candle not visible when seen through the tube. This happens because light generally travels in straight lines, and when it encounters obstacles or bends in its path, it gets scattered or absorbed, leading to a decrease in visibility.

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  • 6. 

    The image formed by a plane mirror is inverted

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    When an object is placed in front of a plane mirror, the image formed appears to be inverted. This is because the light rays that reflect off the object and onto the mirror are reflected back in a way that the top of the object appears to be at the bottom in the image, and vice versa. This phenomenon is due to the fact that the mirror reverses the direction of the light rays, resulting in an inverted image. Therefore, the statement "The image formed by a plane mirror is inverted" is true.

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  • 7. 

    A concave mirror always forms real image

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    A concave mirror can form both real and virtual images depending on the position of the object relative to the focal point. When the object is placed beyond the focal point, a concave mirror forms a real image that is inverted and can be projected onto a screen. However, when the object is placed between the focal point and the mirror, a concave mirror forms a virtual image that is upright and cannot be projected onto a screen. Therefore, the statement that a concave mirror always forms a real image is false.

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  • 8. 

    Any polished or shining surface can act as mirror

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Any polished or shining surface has the ability to reflect light, which is the basic characteristic of a mirror. Mirrors are typically made of glass with a reflective coating, but other materials like metal can also act as mirrors when polished to a high shine. Therefore, it is true that any polished or shining surface can act as a mirror.

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  • 9. 

    A convex lens is thicker in the middle than at the edges

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    A convex lens is thicker in the middle than at the edges because it is designed to converge light rays towards a focal point. The curvature of the lens causes the middle portion to be thicker, allowing it to refract light more strongly and bend it towards the center. This shape enables the lens to focus incoming parallel rays of light to a point, resulting in magnification and convergence.

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  • 10. 

    Out of convex mirror and concave mirror, the focus of convex mirror is situated behind it

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    The statement is true because in a convex mirror, the focus is located behind the mirror. This means that when parallel rays of light are incident on a convex mirror, they appear to diverge from a single point behind the mirror, which is the focus. This is the opposite of a concave mirror, where the focus is situated in front of the mirror.

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  • 11. 

    The lens which feel thinner in the middle than at the edges

    • A.

      Concave

    • B.

      Convex

    Correct Answer
    A. Concave
    Explanation
    A concave lens is thinner in the middle and thicker at the edges. This shape causes light rays passing through the lens to diverge, or spread out. This lens is used to correct nearsightedness, as it causes the light to spread out before reaching the eye, allowing for clearer vision.

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  • 12. 

    The lens known as diverging lens

    • A.

      Concave

    • B.

      Convex

    Correct Answer
    A. Concave
    Explanation
    A concave lens is a lens that is thicker in the middle and thinner at the edges. It is also known as a converging lens because it converges or brings together parallel rays of light that pass through it. This type of lens can form real and virtual images depending on the position of the object. It is commonly used in magnifying glasses, telescopes, and cameras.

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  • 13. 

    The mirror which can form both real as well as virtual images

    • A.

      Concave mirror

    • B.

      Convex mirror

    Correct Answer
    A. Concave mirror
    Explanation
    A concave mirror is capable of forming both real and virtual images. When an object is placed beyond the focal point of a concave mirror, a real inverted image is formed. On the other hand, when the object is placed between the focal point and the mirror, a virtual upright image is formed. This is because a concave mirror converges light rays and can create different types of images depending on the position of the object relative to the mirror. A convex mirror, on the other hand, can only form virtual images that are always smaller and upright.

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  • 14. 

    The lens known as magnifying glass

    • A.

      Convex

    • B.

      Concave

    Correct Answer
    A. Convex
    Explanation
    A convex lens is known as a magnifying glass because it is thicker in the middle and thinner at the edges, causing light rays to converge and focus at a specific point. This allows the lens to magnify objects when they are placed within the focal length of the lens. The convex shape of the lens helps to enlarge the size of the object being viewed, making it appear larger and more detailed.

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  • 15. 

    The large arc of seven colours VIBGYOR in the sky

    • A.

      Rainbow

    • B.

      Shadow

    Correct Answer
    A. Rainbow
    Explanation
    The large arc of seven colors VIBGYOR in the sky refers to a phenomenon known as a rainbow. Rainbows occur when sunlight is refracted, or bent, as it passes through water droplets in the air. This bending of light causes the different colors of the spectrum to separate and form a circular arc in the sky. The colors in a rainbow, from top to bottom, are violet, indigo, blue, green, yellow, orange, and red. Therefore, the correct answer is rainbow.

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  • 16. 

    If the focal length of a concave mirror is 25cm. What is its radius of curvature?

    Correct Answer
    50 CM
    Explanation
    The radius of curvature of a concave mirror is twice its focal length. Therefore, if the focal length is 25 cm, the radius of curvature will be twice that, which is 50 cm.

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  • Current Version
  • Nov 10, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Mar 23, 2014
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    Manickaraj20
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