sample questions unit 6 question 22

**ozy123** · 01-03-2010, 03:30 AM

I'm not understanding how to resolve this at all. Can somebody help me? I'm completely new to the subject material.

I'm not sure where to draw the rays from, the objects or the observer? Or are there returning rays to the observer?

I've looked at the solution. It say it would be 2 or three. How do we know where the focal point is?

It also says we can rule out 3 as its on the same side of the principal axis of the lens as the green bead. How do we know this?

Thanks.

**terrified_tony** · 01-03-2010, 04:44 AM

Its not about focal lengths.. its more about the effects of different types of lenses. I would suggest reading physics textbook on the subject of lenses, it is easier ot learn as a unit rather than trying to learn an abstract purely for the question.
I don't know how you have tried to organise your revision but my advice would be to study the syllabus first and then worry about practice once you have covered the basics to see how you're going along...

**ozy123** · 01-03-2010, 04:59 AM

Thanks for the reply. There isn't a clearly designed sylabus though. Which is why my physics revision is organised purely around finding as many sample questions and taking them on one at a time. I've tried to read the basics around this but have struggled to apply. Can somebody give a more specific answer?

Thanks.

**terrified_tony** · 01-03-2010, 05:12 AM

Without seeing annoying, they state that a good alevel standard of the three sciences is expected and
this would come under a-level physics...

I would draw the rays from the beads through the lens and onto the boards where they would appear.

As it is a converging lense the image is reversed across the principle axis.
In A-level physics you would deal with 2d problems, this is 3d and is typical of a gamsat question,
as it expects the alevel standard, and then asks you to extrapolate the
principle out. Therefore it means that the image is both reversed and inverted by the lens.