posted by Jon on .
1)Which of the following objects can set fire to a piece of paper in the presence of sunlight?
A)doulble concave lens
B, convex lens
2)What happens to a path of a light ray parallel to the principle axis, after it passes through a converging lens?
it passes through focus on the other side of the lens.
all of my answers are from what I understand and not guesses. I can refer to a page in my book to find where and how I arrived at the answer so if some are wrong please don't say I'm taking wild guesses because I'm not doing that
1 and 2 are correct.
It often appears so. You could do yourself a big favor by showing your thinking...that is where we can be used at an advantage, because the analyzing your thinking is what you really need. What if you got the above answers because your thinking was unclear?
For instance, on the second, your thinking is shown. But if the first, you could have said, convex lens, because it focuses the parallel rays of the sun to a single point. But what if you had said, convex lens, because it always makes things hot. Well, we would have caught that thinking.
Other times, on computational problems, such as one recently, you choose the wrong answer, when clearly another answer was correct. What are you expecting, us to work if for you? That usually does no long term good, it helps you much more for us to see your error and point it out. Our purpose here is to help students learn and understand errors in thinking that leads them astray.
You would do yourself a great favor by briefly describing your thinking.