What is Microscope: Definition and 280 Discussions

A microscope (from the Ancient Greek: μικρός, mikrós, "small" and σκοπεῖν, skopeîn, "to look" or "see") is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisible to the eye unless aided by a microscope.
There are many types of microscopes, and they may be grouped in different ways. One way is to describe the method an instrument uses to interact with a sample and produce images, either by sending a beam of light or electrons through a sample in its optical path, by detecting photon emissions from a sample, or by scanning across and a short distance from the surface of a sample using a probe. The most common microscope (and the first to be invented) is the optical microscope, which uses lenses to refract visible light that passed through a thinly sectioned sample to produce an observable image. Other major types of microscopes are the fluorescence microscope, electron microscope (both the transmission electron microscope and the scanning electron microscope) and various types of scanning probe microscopes.

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  1. D

    Strange little microscopic creatures

    Generally I am on the Physics Forum, but I got my hands on a good microscope a while back and decided to grow some little dudes to look at. My third incubation batch consisted of filtered drinking water and a bit of stuff from my mulch pile. Grew a few interesting little guys and looked them...
  2. S

    Building a microscope with two different power lenses

    Homework Statement You've been asked to build a 14X microscope from a 2X magnifying lens and a 5X magnifying lens. What will be the tube length of your microscope? Homework Equations Meye = 25/feye Mobj = -L/fobj M = (Meye)(Mobj) The Attempt at a Solution First, are you supposed to use the...
  3. S

    Solve Microscope Q: Sample Distance w/ 160mm Tube Length & 800X Mag

    Homework Statement A microscope with a tube length of 160 mm achieves a total magnification of 800X with a 40X objective and a 20X eyepiece. The microscope is focused for viewing with a relaxed eye. How far is the sample from the objective lens? Homework Equations M=(Meyepiece)(Mobjective)...
  4. G

    Equipartition Theorem and Microscopic Motion

    Homework Statement What is the typical rotational frequency frot for a molecule like N2 at room temperature (25°C)? Assume that d for this molecule is 10-10m. Take the atomic mass of N2 to be mN2=4.65x10-26kg. You will need to account for rotations around two axes (not just one)...
  5. P

    Methods to stabilize scanning tunneling microscope(STM)

    When the STM becomes unstable(large variations in the current), what procedures should I take in order to fix it? I am new to the STM, but after a few month`s experience I notice that one of the main problems is stabilizing it. When the tunneling current becomes unstable, I`ve tried to...
  6. D

    Gamma Ray Microscope: Can it be Directed and Focused?

    I was in my AP Physics class discussing wavelengths of the electromagnetic spectrum and I came up with the idea to attempt a gamma ray microscope. Of course this is extremely dangerous, so I will have to be cautious (and use a lot of lead). Is there a way to produce gamma rays? I know they...
  7. H

    What precisely IS reflection: what happens at the microscopic level?

    I post in the QM section as an answer in terms of photons rather than just EM waves would be better.
  8. ShayanJ

    Exploring the Complexity of Single Photon QED: Questions and Confusions

    QM started as a non-relativistic theory for microscopic particles. Then there were the attempts to make it relativistic and the results of those attempts suggested that you can't have a relativistic system with a fixed number of particles. But things are a bit different for photons. A...
  9. Choisai

    Microscope magnification with camera

    I have two lenses for my microscope. The object lens which magnifies 63 X. Then there is my eyepiece lens with f=100 mm which focuses the incoming light at an camera. How can I calculate the total magnification? All calculations so far for the eyepiece involve the 25 cm of the human eye, but now...
  10. T

    Angular Magnification for a Microscope

    Homework Statement The eyepiece of a compound microscope has a focal length of 2.50 cm and the objective has a focal length of 1.8 cm. The two lenses are separated by 22 cm. The microscope is used by a person with normal eyes (near point at 25 cm). What is the angular magnification of the...
  11. H

    Hair in between two glass plates. Decreasing the distance between the maxima

    Homework Statement A thin hair is placed between two microscope slides. When laser light is shined down onto the slides, periodic intensity maxima are seen to span the slides. Which of the following changes will decrease the distance between the maxima? I. Decrease the wavelength of the laser...
  12. M

    Is Hawking radiation lethal?

    Wow! Thanks to all for this great resource. Would it be possible to cast light harmlessly by spontaneously creating microscopic black holes of small enough mass? Or would you necessarily get high-frequency X and gamma radiation along with visible light?
  13. bartekac

    Acoustic waves - factors determining their form

    Hi, I am not a native English Speaker, so some words might not be appropriately used below, but I will try my best to explain what I was thinking about. In general, I have never learned how acoustic waves emerge microscopically. The application of the theoretical knowledge I acquired was always...
  14. E

    What Determines the Resolution Limit of a Microscope?

    Hi there! I wonder where the resolution limit for a microscope comes out. I know that the lens can act as a circular aperture of diameter D and so a point source is diffracted in a disk of angular aperture 1.22\lambda/D Two sources are resolved if their distance is greater than (without Abbe...
  15. J

    How does hot water brew coffee?

    I wondering what actually happens when you brew coffee (or tea) with hot water. Every source I can find simply talks about how long you need to brew it to "draw out" the flavor or "release" the caffeine. I'm interested in what's actually physically happening to the coffee grounds that makes it...
  16. O

    Power in electric circuit: apparent contradiction

    Hi, dear forum members! It is well known, that if one makes the current carrying wire more thicker, for example 3 times, that means the current goes up also 3 times. Microscopically that seems plausible, because, when we consider that a cross section is made of atoms, then it is apparent, that...
  17. J

    Quantum physics without probability?

    Will we ever be able to describe the microscopic world , without using the notion of probability? What are the boundaries and restrictions that require probability? As technology , new particles, discoveries, dark matter etc materialize will we eventually be able to measure these...
  18. U

    Optical Transfer Function of a microscope

    Hi all, I am wondering in the 3D optical transfer function as shown below: http://www.purplebark.net/mra/research/votf/otf-sliced-volume.png The m and n axes represent support of lateral spatial frequencies and the s axes axial. If we were talking about a microscope then it has what's called...
  19. R

    Mechanisms of Supercooling and Supersaturation

    I have a couple of questions: The homogeneous freezing temperature of water is listed at -42C. However, from the equations formulated to find critical radius here, I did not see any factors which restricts the homogeneous nucleation temperature to a certain value. How is the homogeneous...
  20. A

    Spec-rel, two ships accelerate away from each other

    Hi all, this is a follow-up variant to an earlier post https://www.physicsforums.com/showthread.php?p=3804580#post3804580 In that post, I wanted to know what an Earth observer would see for a ship some distance off accelerating towards Earth and then reaching constant velocity. For the...
  21. M

    Programs What should I obtain my Bachelor's degree in?

    I am currently a freshman at Penn State University. I have always been greatly interested in astronomy, space, and the universe. Especially cosmology and the "larger pictures" of our existence. I have decided that this is what I want to do with my life...study the universe, help discover new...
  22. S

    Why does superfluid helium in a spinning bucket have angular momentum?

    Suppose you have a bucket filled with superfluid Helium-4 and you spin it with a large angular velocity Ω, the bucket obviously has angular momentum. Spinning fast enough, the fluid develops irrotational vortex lines which carry quanta of angular momentum, while leaving the curl of the ∇xv 0...
  23. S

    Why does the clutch disc disengages the flywheel?

    Hi! I am creating this thread to ask what is the physical phenomena that drive the smooth disengagement of clutch discs from flywheels. I am thinking about car clutches, specifically a longitudinal front engine, rear wheel drive clutch type. I've been reading some books that describe the...
  24. V

    Locate Radio Sources Using Radio Microscope-1 Mhz

    Suppose there is a set of twenty tiny radio sources that are distributed randomly in an area of 1 mm2. What is the best way to locate each of these sources - as in identify them and their locations? We can suppose that all of them are of the same frequency of 1 Mhz. Thus if the radio telescope...
  25. Jackson Lee

    There is little molecule bond between gas molecules, then why we have

    Hey, guys, I have just watced a fantastic animation of the microscopic process of sound wave traveling, in which model was described as many balls connected by springs. But the problem is what we learned in thermodynamics chapter is that there is no bonds between molecules in gas, then how...
  26. StevieTNZ

    Extra-Terrestrial Life Discovered in Outer Space

    At least according to this article, https://nz.news.yahoo.com/a/-/world/24765825/extra-terrestrial-life-discovered-in-outer-space/ An interesting find, to say the least!
  27. M

    Can we "fill" an atom with alpha particles?

    The following passage has been extracted from the book "Modern's abc of Chemistry": Lets fill an isolated atom by subatomic "Rutherford projectiles"-alpha particles. I hope it is possible. This doesn't seem to be a limit of our technology. Isn't it? If we are successful in...
  28. WannabeNewton

    Sphere immersed in classical ideal gas

    Homework Statement A small sphere, with initial temperature ##T##, is immersed in an ideal Boltzmannian gas at temperature ##T_0##. Assuming that the molecules incident on the sphere are first absorbed and then re-emitted with the temperature of the sphere, determine the variation of the...
  29. V

    I need to build a planet. Care to help?

    I know, it sounds a little more epic than it really is. It is true, however. I am in the process of writing a story and would very much like to have the specifics of the other planet described at one point to the reader so they can get a grasp on the world part of the story is taking place in...
  30. Greg Bernhardt

    What is wave-particle duality

    Definition/Summary The double-slit (or 'two-slit') experiment clearly demonstrates that individual particles exhibit a wave-like behavior, in that an interference pattern can be shown to build up over time, despite the presence of only one particle in the experimental apparatus at any given...
  31. Greg Bernhardt

    Understanding Internal Energy in Thermodynamics: Definition and Equations"

    Definition/Summary In thermodynamics, internal energy, U, is the energy associated with the microscopic energies of a system, that is with the energy associated with the random motion of the molecules within a system. More generally, while external energy is energy due to macroscopic...
  32. Greg Bernhardt

    Heat and Work: A Definition and Explanation

    Definition/Summary Heat is the non-mechanical exchange of internal energy, U, between a system and its surroundings as a result of a difference in temperature. By contrast, work, W, is the mechanical exchange of energy as a result of force applied across a moving surface (such as the face...
  33. Greg Bernhardt

    Diffraction Definition & Common Examples

    Definition/Summary Diffraction of a wave is the spreading or reflection or apparent bending when it encounters an aperture, obstruction, or opaque edge. Diffraction by an evenly-spaced series of apertures (a diffraction grating) causes interference patterns and has the same bending or...
  34. I

    How Does Tension Affect Guitar String Frequency Beyond Basic Equations?

    Hi all! I am currently conducting an investigation into the way in which frequency varies when you change the tension on a guitar string. I am aware of Mersenne's laws, and that frequency should vary in square root proportion to tension. I'm looking for an explanation that goes beyond simply...
  35. avorobey

    How does weight add up to press on things?

    I think I understand how pressure works with gases. More molecules bouncing around -> more random impacts -> stronger force. But I realized to my embarrassment that I don't understand how solid things press on each other, microscopically. Say I put a block of iron on my head. If I put...
  36. R

    Optic microscopes. New illumination technic

    Dear friends I have been working on a new way of illuminating microscope specimens. Cannot disclose the innings of it since all is under development. Nevertheless I attach photo since I think you will find it interesting. That is the mouth of a honey Bee, photo compares standard bright-field...
  37. M

    If water molecules are so smallwhy don't they go through skin pores?

    I read that essential oils can go through the skin. I am told that there are more water molecules in just 10 drops of water than stars in the whole universe, so if they are so tiny, why don't they go through the skin membrane pores, which are perfectly visible under an optical microscope? You...
  38. U

    Ray diagrams, lenses and microscopes

    Hi all, I've been reading about biconvex lenses, drawing ray diagrams and real/virtual images. I'm now trying to translate this into how an image is formed in a compound infinity optics microscope. And this has raised some questions: -In an infinity optical system the object is placed at a...
  39. WannabeNewton

    1-dimensional polymer in gravitational field

    Homework Statement A rubber band at temperature ##T## is fastened at one end to a peg and supports from its other end a weight ##W##. Assume as a simple microscopic model of the rubber band that it consists of a linked polymer chain of ##N## segments joined end to end; each segment has length...
  40. G

    Current 3-form, current density, current vector, etc.

    I have been thinking about the Maxwell equations lately and was wondering about their "natural" differential form formulation to get some nice geometric interpretation. This post mainly concerns the inhomogenous microscopic Maxwell equations on some spacetime ##(M,g)##, as the homogenous ones...
  41. J

    Quantum wave bursting out of 100 jars

    Let us consider a quantum wave of one very energetic particle, stored in 100 microscopic jars. There's some lock mechanism that keeps the jar lids on. Then we open all the locks simultaneously. How many lids fly off? One? All?
  42. C

    Good book on light/optics and microscopes

    Hi awesome people at physicsforum, I'm interested in understanding light and optics such that i can understand the basics behind the different types of microscopes (phase-contrast, light microscope, electron emmision etc.). I'm not so interested in the math and calculations, more in the...
  43. D

    Calculating microscopic permittivity

    It has been quite some years since I last used quantum chemistry software. Now I would like to use some program which allows the calculation of the microscopic omega and k-dependent dielectric function (tensor) for periodic crystals. Any proposals?
  44. A

    Is stress tensor symmetric in Navier-Stokes Equation?

    Hello, In CFD computation of the Navier-Stokes Equation, is stress tensor assumed to be symmetric? We know that in NS equation only linear momentum is considered, and the general form of NS equation does not assume that stress tensor is symmetric. Physically, if the tensor is asymmetric then...
  45. E

    Detecting Burned/Distorted Fibers with a Handheld Microscope

    Hello everyone I need to ask in a Hand Held Fiber Optic Microscope what should I see when the fiber is considered burnt or distorted ??
  46. A

    Calculating Maximum Resolution of Electron Microscope

    Homework Statement Electrons are accelerated by 2450 V in an electron microscope. What is the maximum possible resolution? Me=9.11 x 10^-31kg and e= 1.60 x 10^-19 C Homework Equations I'm not so sure which equations to use for this question.. maybe the Planck's formula? λ=h/p...
  47. M

    How Far Should the Object Be Placed in a Microscope Setup for 75x Magnification?

    Homework Statement Suppose we have a microscope made out of two lenses, both with a focal length of 25mm, placed 36.5mm apart. Find how far in front of the first lens should the object be placed to assure that the image is magnified at least by a factor of 75? Homework Equations The...
  48. ~christina~

    Microscope pictures - photomicrographs

    These are some pictures I have taken through the microscope. All of the pictures are of recrystalized ascorbic acid except for the last two. The last two are of NH4 with perchloric acid (clear crystals) and chloroplatinic acid (yellow) respectively...
  49. S

    Microscope for individual cells/bacteria?

    On a whim, I started looking at microscopes on ebay today. I don't really know anything about them though. I'm an amateur astronomer, so I know all about telescopes, but in microscopes, I wouldn't know what to begin to look for. I found this one that's just under $300. It says it will go from...
  50. P

    Scanning Electron Microscope Images

    Would the resulting image by a scanning electron microscope be different if it scanned across the y-axis? SEMs have deflecting coils that move the electron beam from left to right (x-axis) rapidly while traversing down the y-axis to cover the entire specimen. Would the image you get after...
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