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Focusing light

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Lesson details

Lesson outcome

Waxaan sharxi karaa sida iftiinka ka yimaada shay uu muraayad isku-urursan (converging lens) ugu diiradda saaro si uu u sameeyo sawir.

Introduction

In this lesson: I can explain how light from an object can be focused by a converging lens to form an image. Some of the light from objects can pass through a lens and become focused to form an image on a screen. Some light from every point on an object passes through every part of a lens.

Show transcript
Some of the light from objects can pass through a lens and become focused to form an image on a screen. Some light from every point on an object passes through every part of a lens. A convex lens refracts light rays so they travel more towards each other. A point where rays meet is called a focus. All the rays from one point on the object are focused to the same point, forming the corresponding part of the image. The shape of a converging lens refracts (bends) light more at the edges than near to the centre.

Worksheet

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Quizzes

  1. 1. Which of the following statements are correct?

    • Correct answer:Each point on a luminous object emits light in all directions.
    • Each point on a luminous object emits light in one direction.
    • Correct answer:Each point on a non-luminous object reflects light in all directions.
    • Each point on a non-luminous object reflects light in one direction.

  2. 2. A pupil holds up a screen to face the full Moon at night. Which of the following explains why an image of the Moon does not appear on the screen?

    • No light from the Moon hits the screen.
    • The light rays hitting the screen are virtual.
    • Correct answer:Light from every part of the Moon hits every part of the screen.
    • Each point on the screen is hit by light from only one point on the Moon.

  3. 3. A light ray passes from air into a glass block, but it is not refracted. Which of the following statements can explain this?

    • Transmission and refraction cannot happen together.
    • Correct answer:The ray meets the glass along the normal to the block’s surface.
    • The ray meets the glass at 90° to the normal to the block’s surface.
    • Refraction does not happen when light passes from air into a solid.

  4. 4. Light crosses a boundary from one material into another. Which of the following statements is correct?

    • Correct answer:The greater the angle between a ray and the normal, the more it is refracted.
    • The smaller the angle between a ray and the normal, the more it is refracted.
    • The angle between a ray and the normal doesn't affect how much it is refracted.

  5. 5. Which of the following diagrams correctly shows light refracting through a rectangular block?

    • Correct answer:

  1. 1. Which of the following statements about images made on a screen by a convex (converging) lens is correct?

    • A larger lens produces a larger image.
    • The image can be rotated by turning the lens.
    • The image is always the same size as the object.
    • Correct answer:The image is always inverted compared with the object.

  2. 2. A pupil wants to use a lens to make an image of a bright object appear on a screen. Where should the pupil put the screen to see a clear image?

    • at the focal distance from the lens
    • closer to the lens than the focal distance
    • further from the lens than the focal distance
    • Correct answer:It depends on the distance between the lens and the object.

  3. 3. The more powerful a lens is, the shorter its focal length. Which of the following changes would make a lens more powerful?

    • Correct answer:making the lens wider (more curved)
    • making the lens thinner (less curved)
    • making the lens from a material that refracts light less
    • Correct answer:making the lens from a material that refracts light more

  4. 4. The diagram shows a lens focusing light from a tree. Three of the rays are shown. At which of the labelled distances is an image formed?

    • A
    • B
    • C
    • Correct answer:D
    • E

  5. 5. Which of the following happen when a lens forms an image of an object?

    • All rays from one point on the object pass through the same part of the lens.
    • Correct answer:All rays from one point on the object arrive at the same point in the image.
    • Correct answer:Rays from all points on the object pass through each part of the lens.
    • Rays from all points on the object arrive at the same point in the image.

  6. 6. The image shows a convex lens. Which of the following statements about the lens is correct?

    • All parts of the lens refract light equally.
    • The thickest part of the lens refracts light most strongly.
    • Correct answer:The thinnest parts of the lens refract light most strongly.

What pupils see

The same lesson as a pupil sees it. You can set any section as work on its own.

  • IntroductionPrepare
  • Starter quizActivate · 5 questions
  • Lesson videoLearn
  • Exit quizCheck · 6 questions
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