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Why shadows produced due to point source of light have only umbra?
Wiki User
∙ 11y ago
The penumbra is the part of the shadow from which part but not all of the source is
visible. If the source itself is a point source, then either you can see it or you can't,
and there's no such thing as "part but not all" of it, so there's no penumbra.
Wiki User
∙ 11y ago
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What is the size of the shadow and the distance of the object from the light source when a shadow is formed?
If you are using a point light source, the shadow's size is the object's size divided by the distance from the light source to the object multiplied by the distance from the light source to the shadow.
How can an electric bulb be considered as an extended source of light an as point source of light?
Either, depending on the situation. If you look at it from far away, the light seems to come from a single direction, and can be simplified as a point-source. If you are very close, the light comes from different directions, and such a simplification is no longer correct.
Why shadows from one source of light not parallel?
If two people are standing next to each other, and illuminated by a light source, think of this as a triangle. Imagine a line from the light source to person A, and then continuing on. This person will block some of the light and that is the shadow that is cast (along this straight line). Imagine a line from the light source to Person B, and continue that on. This person's shadow will be cast along the line from the light source to him, and continuing on. Since the two lines intersect at the light source, then they are not parallel lines. The farther away the light source is from the two people (relative to their distance from each other) the angle between the lines will decrease, so that they may seem to be almost parallel at some point. The Sun is essentially far enough away that you'd have a difficult time seeing the difference.
What direction do shadows point at noon?
South
What will be the shape of wave front of light coming from a point source place at infinity?
plane wavefront
Is it true that as the sun moves the shadows get longer and point more to the east?
After Noon, when the Sun is highest in the sky and the shadows are smallest, the Sun continues towards its setting in the West. Since shadows are on the opposite side of an object from the light source, the shadows are then on the East side. As the light source gets lower in the sky, the shadows get longer.
What would happen when the moon casts a shadow on the sun?
Nothing casts a shadow on the sun. The sun is the source of light that produces illuminated and shadowed areas, and shadows always point away from the source of light that produces them.
What type of wavefront will emerge from a point source and distant light source?
For a point in space (or from a distant light object), spherical waves are emitted. From a point source on the surface of a liquid, circular waves will come out. In both cases the source will be the focus of the emitted waves.
What is the size of the shadow and the distance of the object from the light source when a shadow is formed?
If you are using a point light source, the shadow's size is the object's size divided by the distance from the light source to the object multiplied by the distance from the light source to the shadow.
How can an electric bulb be considered as an extended source of light an as point source of light?
Either, depending on the situation. If you look at it from far away, the light seems to come from a single direction, and can be simplified as a point-source. If you are very close, the light comes from different directions, and such a simplification is no longer correct.
What is the main source of light in a scene in a three point lighting system?
Key light
Why shadows from one source of light not parallel?
If two people are standing next to each other, and illuminated by a light source, think of this as a triangle. Imagine a line from the light source to person A, and then continuing on. This person will block some of the light and that is the shadow that is cast (along this straight line). Imagine a line from the light source to Person B, and continue that on. This person's shadow will be cast along the line from the light source to him, and continuing on. Since the two lines intersect at the light source, then they are not parallel lines. The farther away the light source is from the two people (relative to their distance from each other) the angle between the lines will decrease, so that they may seem to be almost parallel at some point. The Sun is essentially far enough away that you'd have a difficult time seeing the difference.
What is the main source of light in a scene shot in the three point lighting system?
Key light
What is the main source of light in a scene shot in the three-point lighting system?
Key light
What distance is the light brightest dimmest?
The closer a light source is to your eye, the brighter it appears - intensity included. The closer you are to the source, the larger the angle of the cone; your pupil as the base and the source as the point. The larger the angle from the point, the more light entering your eye. Too close to the source and your retinal area becomes the limiting factor.
Why can't earth's shadow have only an umbra and not a penumbra?
Actually the earth's shadow has both. This is caused by the sun, not the earth. The umbra is the dark shadow produced when the sunlight is totally blocked. The penumbra is the partially lit shadow produced because the sun is not a point light source.
What creates soft shadows in photography?
Sharp shadows are indicators of 'sharp', high-contrast producing lighting. A relatively small light source will produce a sharp shadow regardless of intensity. The son and the moon are large, but are relatively small sources of light. On a bright, clear day you can hold your hand out and cast a shadow of your hand on the ground that is sharp enough to see the fingers. On a bright, clear night you can hold your hand out and cast a shadow of your hand on the ground that is sharp enough to see the fingers against a light surface. Inside, the exact same idea applies. The flash on a camera is a tiny, almost point light source. It always creates sharp shadows. The angle from lens to subject and back to flash is usually very small. A light source never 'sees' the shadows it creates, regardless of how sharp they are. On a clear day or night as the sun or moon is setting, you can minimize the shadows by making sure the light source is behind you as well as you can and that the subject is not too near another object to reveal its shadow. If you were on the moon, the sun would still appear as a small light source. When the relatively small object of the Earth got between you and the tiny light source, it would very quickly become very dark. If you are on Earth for the same occurrence you see the sharp shadow of the planet you are on eclipsing the moon.
