Ray Diagram: Small Bulb & Convex Lens

In summary, the conversation discusses the placement of a small bulb in front of a convex lens and the resulting image location. The first two parts involve drawing a ray diagram using all three principal rays to determine the image location, with the second part showing the image location when the bulb is placed farther from the lens. In part c, it is discussed what would be seen on a paper screen placed at the image location, with the assumption of a dark room and only the small bulb as a light source. Part d involves drawing at least five rays from the bulb that pass through the lens, and the last question asks for the explanation of the image location in this case. The solution involves drawing careful ray traces for the three indicator rays, as well as
  • #1
marla1
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Homework Statement


A small bulb is placed in front of a convex lens.

a) Suppose that the bulb is placed as shown. Using all three principal rays, draw an accurate ray diagram to determine the location of the image. Label the image location.

--------------.F-------0(Lens)-------.F--------------------
.Small bulb

b) Repeat part a for the case shown at right, in which the bulb is farther from the lens.
--------------.F-------0(Lens)-------.F--------------------
.Small bulb

c) Suppose that in each case above you were to place a small paper screen at the image location. What would you see on the screen in each case? Imagine that the room is dark except for the small bulb.

d) The light bulb is placed at one focal point of the lens as shown below. Draw at least five rays from the bulb that pass through the lens.
------------.F(Small bulb at focal point)------0(Lens)-------.F-----------------

Where is the image located in this case? Explain. (Hint: How are the rays that have passed through the lens oriented? From where do these rays appear to have come?)

Homework Equations


Not sure?

The Attempt at a Solution


For part a, I think there would be a parallelogram-shaped diagram through the top middle and bottom of lens.

For part b, as the small bulb moves further away, I think the diagram would flip?

For part c, if you placed a small paper screen, I think you would see a circle of light?

For part d, I think the five rays would be evenly spaced throughout the lens.

For the last question, The image would be located in front of the lens?

Help with this problem/thoughts/answers/reasoning would be EXTREMELY helpful! Thanks in advance! See better pictures/sheet attached.
 

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  • #2
You need to carefully draw and submit careful ray traces for thr three indicator rays (acually there are an infinite number for the object at focus). That is the only good way to proceed.
 

1) What is a ray diagram and how is it used in studying light and lenses?

A ray diagram is a visual representation of how light rays behave when they interact with a lens. It is used to study and understand the properties of light and lenses, such as how they refract or bend light, and how they form images.

2) What is the difference between a convex lens and a concave lens in terms of their ray diagrams?

A convex lens is thicker in the middle and thinner at the edges, while a concave lens is thinner in the middle and thicker at the edges. In terms of their ray diagrams, a convex lens will converge light rays to a focal point, while a concave lens will diverge light rays away from a focal point.

3) How does the position of the object and the lens affect the ray diagram in a small bulb and convex lens setup?

The position of the object and the lens will determine the size and location of the image formed by the lens. If the object is closer to the lens, the image will be larger and located further away. If the object is further away, the image will be smaller and located closer to the lens.

4) Why is it important to use a small bulb in a ray diagram with a convex lens?

Using a small bulb allows for a simplified ray diagram, as it allows for only two principal rays to be drawn - the ray parallel to the principal axis that passes through the focal point, and the ray that passes through the center of the lens. This makes it easier to accurately determine the location and size of the image formed by the lens.

5) How does the curvature of a convex lens affect the ray diagram?

The curvature of a convex lens, also known as its focal length, affects the amount of bending of light rays passing through it. A more curved lens will have a shorter focal length, causing light rays to converge more strongly and form a larger image. A less curved lens will have a longer focal length, causing light rays to converge less and form a smaller image.

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