Physics · Optics

Khám phá sự tạo ảnh qua thấu kính hội tụ

Exploration tips

Where to start

Press the five position presets one by one, or drag the object arrow directly along the optical axis. After each move, read the conclusion line right above the diagram.

Try and compare

Move the object inward from beyond 2F: how large does the image grow before it changes from smaller to equal then larger than the object? Turn on the third ray to check whether all three rays meet at one point.

Open question

Why is there no image exactly at the focus? Try changing the focal length and placing the object back at F to see whether the conclusion changes. Can a virtual image be caught on a screen?

Object beyond 2FReal image · inverted · smaller than the object

Object (solid)
Real image (solid)
Virtual image (dashed)
Parallel ray
Ray through the optical center
Ray through the focus

Special positions

Object distance d30 cm

Focal length f10 cm

Object height h5 cm

Image-forming rays

Incident ray parallel to the optical axisEmerges through the focal point behind the lens.Ray through the optical centerTravels straight without changing direction.Incident ray through the object-side focal pointEmerges parallel to the optical axis.

Distance rulerImage screenDrag the screen on the diagram to find where the image is sharp.

Real image – inverted – smaller than the object.

When d > 2f, the real image lies between F′ and 2F′, inverted and smaller than the object.

Why it happens

The farther the object moves beyond 2F, the closer the image moves to F′ and the smaller it becomes. Moving the object toward 2F makes the image grow.

Parameters

Focal length f: 10 cm
Object d: 30 cm
Magnification k: −0,5
Image height |h′|: 2,5 cm
Image distance d′: 15 cm (behind the lens)

Place the object so that the image is the same size as the objectThere is a unique position for an image exactly equal to the object.Not completed
Create a virtual, upright and larger imageTry moving the object very close to the lens.Not completed
Find the position that sends the image very far from the lensApproach the focus from the outside and watch d′.Not completed

Model notes

The lens is thin and ideal: thickness, aberrations and aperture limits are ignored.
Light travels from left to right; the object is real and placed perpendicular to the optical axis.
The image follows the lens equation 1/f = 1/d + 1/d′ and the magnification k = −d′/d.
The horizontal and vertical scales differ so the diagram is readable; this does not change the intersection point of the rays.
The blur on the screen is a qualitative description of the right trend (the more the screen is off the image position, the blurrier it is), not a quantitative optical measurement.
Zooming, panning or dragging the view only changes the viewing angle, not any physical quantity.

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Khám phá sự tạo ảnh qua thấu kính hội tụ

Where to start

Try and compare

Open question

Parameters

Conclusion

Parameters

Exploration tasks

Khám phá sự tạo ảnh qua thấu kính hội tụ

Where to start

Try and compare

Open question

Parameters

Conclusion

Parameters

Exploration tasks

Where to start

Try and compare

Open question

Converging lens simulation area

Parameters

Conclusion

Parameters

Exploration tasks

Where to start

Try and compare

Open question

Converging lens simulation area

Parameters

Conclusion

Parameters

Exploration tasks