Changing the focal point

when you decrease refractive index of lens, rays bend less and therefore less steep angle so focal point is larger. but what happens to the image? is the image larger also?

when you ie increase curvature, do the rays travel at more of an angle?? as f=r/2, i assume as when the lens is more curved, radius is smaller and so F is smaller. but when F is smaller what happens to the image and why?

Hi Mego, great questions.

Phet have a great simulator you can use to experiment with lens properties and see the effect on an image.

Assuming your object is located beyond F, then a real image would get larger as F increases

In an exam I would recommend sketching two ray diagrams to check your answer.

When discussing refraction, I would refer to the ‘change in direction’ of the rays, rather than saying they ‘bend’. You are correct about the radius being smaller with a more curved lens, and a smaller F. To fully answer your question about the propoerties of the image, we may need to consider where the object is in relation to the lens, and whether a virtual or real image is formed. Try moving the object on the simulation to see how different images can be formed.