To improve magnification. Also so that we can get a real and inverted image
The small aperture and focal length of a microscope objective allow for high resolution and magnification by increasing light-gathering ability and minimizing aberrations. A small aperture increases depth of field and improves contrast, while a short focal length reduces spherical aberration and increases optical performance.
The main parts of an optical microscope are: the eyepiece, objective lense and light source (sometimes a mirror). The objective lense has a short focal length so it produces an image a little bit up the microscope's tube which is then magnified by the eyepiece. Resolution is dependant on the numerical appeture of the lense and the wavelenght of the light source used.
A lens with a long focal length is typically used in the Newton's rings experiment. This is because a longer focal length helps produce a larger, more distinct interference pattern, making it easier to observe and measure the rings.
The power of a lens is measured in dioptres which is the reciprocal of the focal length in metres. A 5-dioptre lens would allow you to see something at a distance of 20 cm, while a 20-dioptre lens would allow the object to be seen from 5 cm (2 inches) so it would be more effective as a magnifying glass. Your arms are short.
A confocal microscope works by a laser shining on two mirrors mounted on motors which allows it to scan the sample then the emitted light is focued through the pinhole to a detector which relays an image to the lens.
The small aperture and focal length of a microscope objective allow for high resolution and magnification by increasing light-gathering ability and minimizing aberrations. A small aperture increases depth of field and improves contrast, while a short focal length reduces spherical aberration and increases optical performance.
compound microscope consists of 2 lences of short focal length & short aurpature .
In a modern light microscope, the term "compound" refers to the presence of multiple lenses (objective and eyepiece) that work together to magnify the specimen. This setup allows for higher magnification and resolution compared to simple microscopes, making it ideal for observing smaller structures in detail.
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.
The size (diameter) of a lens does not determine its focal length. The amount of curvature of the lens does. Citing a diameter for a lens doesn't help us find the focal length. Lenses are ground to specifications that allow short or long focal length. The more curved the lens, the shorter the focal length. You can see this if we specify a given curvature and then start to "flatten" the lens. The focal length will get longer and longer as the lens is flattened. When the lens is flat (has to curvature) the lense has an infinite focal length, just like a piece of flat glass.
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.
A high-power objective lens with a large numerical aperture and short focal length would allow for greater magnification on a microscope. This lens can capture more light and details due to its ability to gather light rays at wider angles. Combining this lens with suitable eyepieces can further enhance the magnification level.
Technically the shorter the focal length, the thicker the mirror. But some short focal length telescopes have relatively thin mirrors all the same.
a camera? Or an eye? Something like that. Weird question
The main parts of an optical microscope are: the eyepiece, objective lense and light source (sometimes a mirror). The objective lense has a short focal length so it produces an image a little bit up the microscope's tube which is then magnified by the eyepiece. Resolution is dependant on the numerical appeture of the lense and the wavelenght of the light source used.
Wide-angle lenses have a short focal length. The focal character of my short story is a ten-year-old boy.
That is certainly not true. A "compound" microscope is one that has an objective AND an ocular. Typically the front focal distance is so short that illumination through the specimen is most common. A "simple" microscope has only one magnifying lens group, not two or more. Short front focus makes lighting from the side more difficult but not impossible or even rare.