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immersion

In light microscopy, oil immersion is a technique used to increase the resolving power of a microscope. This is achieved by immersing both the objective lens and the specimen in a transparent oil of high refractive index, thereby increasing the numerical aperture of the objective lens.
Without oil, light waves reflect off the slide specimen through the glass cover slip, through the air, and into the microscope lens (see the colored figure to the right). Unless a wave comes out at a 90-degree angle, it bends when it hits a new substance, the amount of bend depending on the angle. This distorts the image. Air has a very different index of refraction from glass, making for a larger bend compared to oil, which has an index more similar to glass. Specially manufactured oil can have nearly exactly the same refractive index as glass, making an oil immersed lens nearly as effective as having entirely glass to the sample (which would be impractical).
Immersion oils are transparent oils that have specific optical and viscosity characteristics necessary for use in microscopy. Typical oils used have an index of refraction of around 1.515. An oil immersion objective is an objective lens specially designed to be used in this way. Many condensers also give optimal resolution when the condenser lens is immersed in oil.

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  1. C

    Hot tank with two immersion heaters

    Hi everyone I have a 20 year old Megaflo CL250 indirect hot water tank that I typically heat with an oil-fired boiler. It has locations for two immersion heaters (one at the base of the tank and the other halfway up). Only the lower immersion is installed and the other (halfway up the tank) is...
  2. T

    What size thread for Immersion Heating Element?

    Hi, I want to fit an immersion heating element to my hot water tank (water is currently heated by gas). I'd like to buy it before I start draining water from the tank. The plug in the tank has a 1 1/4" nut on a pate approx 3" in diameter, does anybody know what size thread the tank will have...
  3. P

    Immersion diversion advise

    Hi all, I'm just after some knowledge to something i came across today. I was asked how a direct unvented cylinder worked in an apartment a few doors down to where i was working. The couple just moved in and wanted some advice, They had only been in the apartment for two days and used to have a...
  4. S

    Immersion Heater Overheating & Kettling

    Hi All, My nans hot water recently stopped working which resulted in an extremly over priced plumber coming out and replacing both elements in the immersion tank. Aside from a huge price tag, it seemed the issue was resolved... until a few weeks back The cut off switch keeps going off if the...
  5. R

    Immersion heater has water in the cap

    My immersion heater tripped the mains breaker, when I took the cap off it was full of water and the element seems to be shorted to earth. It's been there for a while so ok I need a new one but how is the water getting into the cap. I cleaned it up and left the cap off check next day full of...
  6. U

    Why do I have to keep re-setting the immersion heater thermostat

    Dear All, My hot water cylinder (approx 45 years old) is fitted with a bottom mounted immersion heater controlled via a timer and an Essentials 7" TS220 thermostat bought from Screwfix. The cylinder itself is well lagged with two jackets and the timer kicks in every evening for 3 hours...
  7. Jeffrey Griffin

    dual immersion reset button melted!

    hi there. immersion hasnt been heating water. tests resistance and wiring and all is ok. but the reset button had melted!! without going to the hassle of replacing the entire immersion would it be possible just to swop out the thermostat for one with a rest button on it and connect the wiring...
  8. G

    Any gotcha's to drain and refill a hotwater tank to replace 2 x immersion heaters?

    My daughter has all electric heating, however, the lower economy 7 immersion has failed (high resistance short to earth). I received what I consider a ridiculously high quote of over £400 to drain the tank and replace both immersions (upper boost immersion is working but 8 years old so I assume...
  9. A

    Boiler broken and using immersion heater for the first time!

    Hi all! Need some newbie advice please... I have an unvented system boiler set up and the boiler has broken down due to pressure loss (engineer coming monday) I have switched off the boiler. The hot water cylinder has an immersion heater element, is it simply a case of turning the element on...
  10. MrGatch

    Burning Smell and Flames on Electrical Immersion

    I have a smell of burning from the immersion on hot water cylinder. The overheat pin had popped out, but when I popped it back in and switched on there were tiny smouldering flames around one of the contacts where the thermostat connects to the immersion. Separately I've replaced the timer as...
  11. B

    Willis Immersion issue - no hot water getting to main tank

    Replaced a Willis (Belfast) immersion heating in an open vent heating system. Willis is working ok but flow of heated water see wrong and does not generate a lot of hot water. Symptoms are (See diagram): Flow from hot tapes fine (no air locks). Tank heats up using house oil indirect heating...
  12. MrGatch

    Immersion Cover Nuts

    Hi, I've just bought two new plastic covers for cylinder immersion heaters as they are both missing on the cylinder. Does anyone know what the thread size for the small securing nuts that I need to attach the covers to the immersion? Thanks
  13. B

    What power cable for immersion heater?

    An easy one... The power cable from my immersion heater controller to the heater itself needs replacing. It's been stripped back so many times over the years that it's getting too short. Can someone qualified tell me exactly what cable to ask for? From what I've read, it would be a three-core...
  14. B

    Replacing "short wire" in immersion heater

    Hi, This morning, I found that my immersion heater had stopped working. The short wire that runs from the thermostat to the live terminal of the heater had fried (or at least its insulation did) and disconnected from the terminal pin. Although I've scavenged a replacement wire from an old...
  15. T

    Pullin Immersion Heater 3KW 240 V

    Hi, I'm looking to have this replaced because it is tripping the power when I turn it on. This isn't my photo. I found it via google image search. It is exactly the same as mine though with that label with the name/ address etc. It must be at least 25 years old. Can you still find these...
  16. Reddwarf4ever

    Hot water temperature from Domestic immersion cylinder

    I have my immersion cylinder thermostat fitted to wall, at 90 deg to the inlet from the diverted valve, was told this was the best position. I have a digital thermometer fitted at this point and it shows 43oC with an outlet temperature of 54oC, measured with an oven thermometer inserted...
  17. Ankle_Deep

    Does my immersion element need replacing?

    I'd appreciate some guidance on whether my thinking is right: Direct feed, immersion-only tank, probably about 15 years old. Lower, side-entry element stopped heating the water at night. Testing showed that the timer was no longer switching the relay, so I replaced it. Since then, it has not...
  18. C

    What size immersion for 117L 900 x 450 cylinder?

    So i'm a 4th year apprentice doing gas repairs and servicing, don't really get involved in cylinders too much unless changing a 3port or something because at my company the plumbing department change all cylinders I've got a private job of changing the above cylinder due to it leaking in...
  19. J

    Changing unvented cylinder immersion element

    Hi all, I"ve got my G3 unvented. Customer wants an immersion element changing. Access is limited - once I get into the cupboard, and I do my electrical tests it hopefully might just be the stat that needs swapping. However, if it is the element... words of advice and tips would be...
  20. G

    Immersion Heater Thermostat Problem

    Afternoon Ladies & Gents, I am having a repeat problem with my Grandma's Immersion Heater Thermostat. The thermostat is a 18" Tesla Dual safety variety from Screwfix. Grandma had a new cylinder and header tank fitted with immersion heater, no other source of hot water. I have replaced the...
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