# Questions about Objects and Light

william87
Hello,

I am taking Intro to Physics, and I have came across with a few problems that don't know how to solve.

## Homework Statement

What my teacher has told me: An image is aid to be located where the rays which enter the eye appear to come from. And when light strikes the center of the flat side of a transparent D shaped lamina, it will travel almong a radius to the curved surce and so will not refract (bend) on exiting the "D".

What I know: The angle of incidence always equals the angle of reflection (measured from the normal). And the properties of light:
1. Travels in a straight line
2. At surface, either reflectss, transmits, absorbed, or all the above
3. Must enters eye to be seen
4. Light continues to travel until it's blocked by an object
5. In order to see a certain object, I need to be in the path of light that comes off the object
6. Angle of reflection = Angle of incidence

## Homework Equations

1.Suppose two people stand in different locations and act as observers. They each report to you that they see a particular object and they each give you precise information about their line of sight. (For example “25° South of East” or a similar statement.) How can you use this information about the location and line of sight from each observer to find the location of the object?

2.We immediately recognize things as being to the right or left of other things. And yet we do not actually move our head from one object to the other, nor do we touch the two objects to confirm their locations with our tactile senses. What we do is to turn our eyes/head to receive light that approaches from a different angle. In your ray diagram show what property or feature of the rays from different objects helps us determine the right left ordering of those objects in our field of view.

3.The most obvious method of judging depth is to note that one object blocks the light from another. Show how this works with a ray diagram. Make it explicitly clear how we know which object is ahead and which is behind.

4.Light diverges from object points. When the object is close to us, the angle of divergence is greater than when the object is further away. Assume that the eye-brain system is very sensitive to the angle your eyes are directed. From this, explain how binocular vision allows us to judge depth.

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Homework Helper
Welcome to PF!

Hi william87! Welcome to PF!
1.Suppose two people stand in different locations and act as observers. They each report to you that they see a particular object and they each give you precise information about their line of sight. (For example “25° South of East” or a similar statement.) How can you use this information about the location and line of sight from each observer to find the location of the object?

We're only allowed to help you, of course, not do the question for you. So …

Hint: draw a triangle!
2.We immediately recognize things as being to the right or left of other things. And yet we do not actually move our head from one object to the other, nor do we touch the two objects to confirm their locations with our tactile senses. What we do is to turn our eyes/head to receive light that approaches from a different angle. In your ray diagram show what property or feature of the rays from different objects helps us determine the right left ordering of those objects in our field of view.

Hint: when you draw the diagram, label all the angles clearly (preferably with consecutive characters, like a b c d e … or 1 2 3 4 5 …).

Then describe what you see … a lot of physics is just knowing how to describe something in slightly mathematical language!

ok … try 1 and 2 for yourself, and come back if you're worried about anything!

william87
Hi william87! Welcome to PF!

We're only allowed to help you, of course, not do the question for you. So …

Hint: draw a triangle!

Hint: when you draw the diagram, label all the angles clearly (preferably with consecutive characters, like a b c d e … or 1 2 3 4 5 …).

Then describe what you see … a lot of physics is just knowing how to describe something in slightly mathematical language!

ok … try 1 and 2 for yourself, and come back if you're worried about anything!

Thank you for your reply, tiny-tim. I will try out the questions right now and if I come across with some problems, then I will definitely come back and ask for your assistance.