Converging Lens Worksheet
Goal: Use the thin-lens equation 1/f = 1/dₒ + 1/dᵢ to predict where a converging lens forms an image, and whether it is real or virtual, inverted or upright, larger or smaller.
What to do
- Press Reset, then “Real image” (f = 10 cm, object at 25 cm). Record the image distance, magnification, image type and orientation.
- Press “Same size”, “At the focus” and “Magnifier” in turn, and record a row for each.
- Press “Real image”, then set the Object distance to 15 cm, and then to 40 cm. Record both rows.
Record your results
| Setting | Image distance | Magnification | Image type | Orientation |
|---|---|---|---|---|
| Object at 25 cm (Real image) | ||||
| Object at 20 cm (Same size) | ||||
| Object at 10 cm (At the focus) | ||||
| Object at 6 cm (Magnifier) | ||||
| Object at 15 cm | ||||
| Object at 40 cm |
Questions
Use 1/f = 1/dₒ + 1/dᵢ to calculate the image distance for the object at 25 cm. Does it match the lab?
When is the image the same size as the object? Explain with the magnification M = −dᵢ/dₒ.
As you moved the object from 40 cm to 15 cm, what happened to the image?
What happened when the object was exactly at the focal point (10 cm)?
With the object at 6 cm, inside the focal length, the image distance is negative. What does that mean, and where is this used?
Challenge: predict where the image forms for an object 60 cm from the same lens, then check it.
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