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Convex lenses and images

Change the object distance and focal length to check the real image, virtual image, and magnification.

    P14 · Convex lenses and images0.00 s · Ready
    Change the object distance and focal length to check the real image, virtual image, and magnification.

    Physics/Optics/Principles and Exploration

    Convex lenses and images — principles and investigation

    Find out why objects viewed through a convex lens sometimes appear enlarged and sometimes appear upside down. Follow the location where the representative rays meet while adjusting the object distance, height, and focal length. This is a lens experiment that distinguishes between real and virtual images, upright images and inverted images.

    How does it work?

    Outside of focus is an upside-down reality, and inside focus is a straight illusion. It indicates that no image is formed above the focus.

    Key relationship

    1/a + 1/b = 1/f · m = −b/a

    Try this investigation

    1. Drag the object or move the slider to observe the three rays and images.
    2. Record object distances 30, 20, and 15 cm at f=10 cm.
    3. Record conditions such as being in focus, in focus, and changing only the focus distance.

    Interpreting your results

    What are the image distance and magnification size when f=10 cm and a=30 cm?

    b=af/(a−f)=15 cm and m=−b/a=−0.5, so it is half the size upside down.

    Assumptions and limitations

    This is a paraxial ray model of a thin ideal convex lens. Lens thickness, aberration, diffraction, and finite aperture are omitted. The horizontal and vertical enlargements were drawn differently. Large images and rays near the focus are cut off the screen, but leave the actual calculated values ​​in the table. There is no finite distance image at a=f.