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When you measure focal length why do you have to use natural light?
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What is the formula for light gathering power for telescopes?
For visual observation: Magnification = (Focal Length of Objective Lens) divided by (Focal Length of Eyepiece) (They have to be measured in the same units.) For prime-focus photography: (One focal-length of the Objective Lens on the film) = (one radian in the sky)
How you can find focal length of plane?
When light passes through the glass plate, the light doesn't bent so the focal length becomes infinity. And we have power=1/focal length, so power remains zero.
What is the significance of the term compound in describing a modern light microscope?
A compound microscope contains an objective lens with a very short focal length and an eyepiece with a longer focal length. Both lens are mounted in the same tube.
What is a accommodation pupillary reflex?
Adjustment of the focal length of the lens of the eye, to accomodate the various light rays from various distances.
The magnification of a telescope is changed by changing the what?
The magnification of a telescope is the ratio of the effective focal length of the objective to the focal length of the eyepiece. For example, a small telescope's objective may have a focal length of 800mm. When an eyepiece with a focal length of 25mm is used, the magnification is 800/25 = 32. The term "effective focal length" refers to the focal length of the objective as affected by any "focal extender". Many telescopes are designed to have a short total size, but high power, by "folding" the optical path. A mirror-type objective with a focal length of perhaps 800mm is coupled with a smaller curved mirror that intercepts the last 200mm and extends it to 800mm, a 4x extension, so that the effective focal length of that objective is 3200mm. Use that with a 25mm eyepiece and the magnification is 3200/25 = 128. By the way, if a telescope is smaller than you are, it is seldom much use to view using a magnification greater than 50 to 100. Most objects are best viewed at relatively low powers such as 30 or so.
What is the positive lens is the same as?
The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror. The focal length of an optical system is a measure of how strongly the system converges or diverges light.
Explain how the focal length changes as a convex lens becomes flatter?
The focal length of a lens is the distance from the center of the lens to the point at which it focuses light rays. The bigger the focal length, the more powerful the lens. ChaCha!
Difference between focal point and focal length?
The focal point is the point where light converges after it passes through a concave lens. The focal length is the distance of the focal point to the lens. Same for a convex lens, except that the focal point is the imaginary point from where light deflected from lens seems to have emerged.
What is the formula for light gathering power for telescopes?
For visual observation: Magnification = (Focal Length of Objective Lens) divided by (Focal Length of Eyepiece) (They have to be measured in the same units.) For prime-focus photography: (One focal-length of the Objective Lens on the film) = (one radian in the sky)
How do you measure a focal length?
The formula for focal length is given byÊ1 divided by 1/a plus 1/b, where 'a' is the distance to a lamp or light source and 'b' is the distance to the wall. You find the focal length by placing a lens parallel to a white wall and focus a light source through the lens until one gets a clear image. The lamp has to be positioned so that it is close to the optical axis of the lens.
How you can find focal length of plane?
When light passes through the glass plate, the light doesn't bent so the focal length becomes infinity. And we have power=1/focal length, so power remains zero.
What will happen to the focal length of a concave mirror or a convex mirror when the incident violet light on them is replaced by red light?
Nothing. The focal length is defined as point where all of the light converges after passing through the lens ( for a convex mirror)and only depends on the mirror's curvature. So changing the incident light ray will cause no change in the focal length of the mirror.
How is the focal length of a spherical mirror affected when the wavelength of light used is increased?
The focal length does not depend upon the wavelength or the frequency so it remains unaffected.
Why do people use the lights from a window instead of using the room lights when measuring the focal length of a convex lens?
Light coming from a distance will be made up of relatively parallel rays of light. Making the approximation to the focal length (by means of a ray diagram) more accurate than if you used a light source that is at a distance comparable to that of the lens' focal length.
Estimate the focal length of a typical magnifying mirror that you might purchase from a drugstore?
Reflect the sun's light with the mirror onto some kind of target. Find the distance where the dot of light is smallest. That distance is the focal length.
How does the eyepiece affect the total magnifacation in a telescope?
A telescope consists of two lenses. 1) The main lens which collects the light ( it is relatively bigger that eyepiece). 2) Eye piece , through which we see. Magnification of a telescope depends on the focal length of the eye piece and the main lens. Magnification = Focal length of the main lens / Focal length of the eyepiece . For example : If the focal length of the main lens is 12 units and the focal length of the eyepiece is 2 units , then the magnification will be 12/2 = 6.When the focal length of the main lens is constant , the focal length of the eyepiece is inversely proportional to the magnification.
Does focal length of convex lens depend on colour of light used?
yes, of course
