Producing umbra and penumbra with light sources

In summary: When three sources are used, how many sources must be blocked by the object to produce the unbra? and the penumbra?In summary, both have to be blocked for the "umbra", only one for the "penumbra".
  • #1
queen2020
10
0
when two souces are used, how many sources must be blocked by the object to produce the unbra? and the penumbra?

I looked it up in my textbook and on the internet and i still can't find the answer.
 
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  • #2
help please

Can someone help me please
 
  • #3
Both have to be blocked for the "umbra", only one for the "penumbra".
 
  • #4
Do you know the definitions of umbra and penumbra? The answers should have been obvious. Even doing something as crude as punching

"define umbra"
"define penumbra"

into google and looking at the web definitions gives us phrases like:

For penumbra:
"Literally partial shadow; the partially lighted area around any completely darkened area (umbra) of full shadow."
"The shadow that results when only part of the bright object is occulted"
"region of partial shadow that is outside the umbra; the light source is partially blocked."

For umbra:
"The area of total darkness in the shadow caused by an eclipse."
"The umbra is the area of total shadow (compare to penumbra)."
"The portion of a shadow that receives no direct light from the light source."
 
  • #5
thank you so much
 
  • #6
I need help with shadows

When three sources are used, how many sources must be blocked by the object to produce the umbra? the dark penumbra? and the light penumbra?

Could anybody help me please.
 
  • #7
Have you tried at all to figure it out yourself?
 
  • #8
yes i have tried to figure it out but i can't figure it out at all
 
  • #9
In your own words, what are the definitions of "umbra", "dark penumbra", and "light penumbra"?

Can you at least identify the conditions on being in the umbra or penumbra?
 
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  • #10
The umbra is part of the shadow that is entirely dark. i don't know the definitions of dark penumbra or light penumbra.
 
  • #11
Ok, that's good. Can you describe the penumbra? Do you have a guess as to what "light penumbra" and "dark penumbra" mean? I think that "light" and "dark" weren't being used as technical terms here, just descriptive.
 
  • #12
so i would put a part where some light falls.
 
  • #13
I don't understand what you've suggested.
 
  • #14
When three sources are used, how many sources must be blocked by the object to produce the umbra? the dark penumbra? and the light penumbra?
 
  • #15
Didn't you already figure one of those questions out?
 
  • #16
i don't know
 
  • #17
queen2020 said:
i don't know

Draw yourself some diagrams. If you have one light source blocked by an object, there will be a shadow that has an umbra and a penumbra. If the shadow falls on a screen, you can draw the umbra and penumbra areas that hit the screen. I will assume you know what those are. If you have two light sources, each source will have its own umbra region and penumbra region behind the object. On a screen, there may or may not be some umbra overlap, some region where the umbra of one shadow overlays the penumbra of a second shadow, and some regions where only penumbra overlap. There could be no overlap at all if the screen is too far away from the object, but you can move the screen closer to get all the different kinds of overlap that are possible. With three sources you can have more combinations of overlap contitions including: three umbra overlap, two umbra and one penumbra, one umbra and two penumbra, three penumbra. Try to sketch these various possibilities as they might appear on a screen and then answer the question.
 

1. What is the difference between umbra and penumbra?

Umbra and penumbra are both dark areas that are created by blocking light. However, the main difference between them is the level of darkness. Umbra is the darkest part of a shadow, where no direct light can reach, while penumbra is a partially shaded area where some light can still reach.

2. How can light sources be used to produce umbra and penumbra?

Light sources can be used to produce umbra and penumbra by placing an object in the path of the light. The object will create a shadow, with the darkest part being the umbra and the lighter part being the penumbra. The size and distance of the light source, as well as the shape and distance of the object, will affect the size and intensity of the umbra and penumbra.

3. Can any light source produce umbra and penumbra?

Yes, any light source can produce umbra and penumbra as long as it is blocked by an object. However, the size and distance of the light source will affect the size and intensity of the umbra and penumbra, with larger and closer light sources producing larger and darker shadows.

4. What are some real-world examples of umbra and penumbra?

Real-world examples of umbra and penumbra can be seen when an object blocks sunlight, creating a shadow on the ground. Another example is when a person stands in front of a lamp, creating a shadow on the wall behind them. The eclipse of the sun by the moon is also an example of umbra and penumbra, with the moon casting a dark umbra and a lighter penumbra on the Earth.

5. How are umbra and penumbra used in scientific research?

Umbra and penumbra are important in scientific research, especially in the fields of astronomy and physics. For example, studying the umbra and penumbra of a solar eclipse can provide information about the size and shape of the moon, as well as the distance between the Earth and the moon. In physics, the study of light and shadow can help us understand how light behaves and how it can be manipulated.

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