Lab Equipment: Magnetic Stir Plate

One of the most basic pieces of lab equipment is the stir plate. We get a lot people asking how our chemicals magically stir themselves so hopefully this video will shed some light on that.

Now that we've shown you one and what's inside. STOP ASKING ABOUT IT!!!!

:)

Category:

Science & Technology

Tags:

• magnetic
• stir
• plate
• lab
• equipment

[ApertureScience27]

Seems kinda stupid to have a motor inside the device spinning a magnet. Why not make it solid-state with coils that reverse polarity? Basically an induction motor with the stir bar as the rotor.

[NurdRage]

@ApertureScience27 i'm not an engineer so i can't say for certain. But i think the electromagentic field required to strongly couple to the magnet would require a lot of current and would waste power (since the coils have a small resistance). But by having a permanent magnet the strong magnetic field is free since it doesn't need power to run. This field couples to the stirring magnet and so you only need to expend energy in actually turning the assembly, which uses far less power

[bas12345654321]

@NurdRage

(2 reactions becouse not enough caracters availeble)

1. If the frequenty lowers, the current will get to high so your coils will burn out.(could be prevented with a propper current cource.)

2. The coils makes high voltages when turned on or off, that would demolish your driver circuit.

The current trough the heating element will also effect the rotating field of coils.

[NurdRage]

@bas12345654321 oh i'm not the one that needs an explanation, its the other posters that do, :)

[Yoachan]

I want to see your face. :D 

please.

[vvvcodevvv]

Now I know!!!!

[therealjammit]

@ApertureScience27 IEEE here. As stated below, induction motors would draw a lot of current at low frequencies. Adding a magnet to a spinning motor is cheaper and draws less power, plus you can get really slow spins.

[Venom2U]

You asked if there was another piece of lab equipment we would like to see. IDK about others but, a Friedrichs condenser gets me all twisted. I can’t tell from the wiki pic what pathways are for what. IE vapor path VS coolant. Moreover what is a Friedrichs condenser used for? From looking at it, it appears to be a type of fractional distillation column. (like a snyder or a vigreux column) But I don’t understand why it has such a specialized shape as opposed to other types..... thanks

[2m11christian]

nurd rage what does your face look like O3o



[DeluxeWarPlaya]

This apparatus is blindingly obvious as to how it works.

[professorjoseph]

I do not consider too many people bright or clever in anyway but must admit you have impressed me more than once primarily because you are a good teacher and take the iniative to aid your fellow nurd. I thank you very much.

[Sophesumer]

@ApertureScience27

Oh, and forgot to mention- another problem:

-For your electromagnets to be powerful enough to stir with any torque at all, you're going to have to use iron cores, and in that case how do you prevent the stir bar from being attracted to the core materials through the plate?

[Sophesumer]

@ApertureScience27

Here are a few problems to conquer if you want to design it:

-How do you place enough electromagnets in a circle to provide a smooth spinning action to the stir bar while still being powerful enough to move the stir bar?

-How do you prevent loss of coupling whereby the stir bar goes flying off in some direction, or spins at a rate different than the rate at which the fields change?

Its just way harder to design a solid state magnetic stirer, and not really necessary.

[thedarkone2134]

@labobo "decent school"

Hence the problem. Science funding for schools is terrible now.

[bas12345654321]

@NurdRage

Yes I know,

Thats why i posted the comment, but its 2 comments long.

So it gets a bit messy.

something else,

I did reply to 2 of your videos, can you anser them?

1. Get Zinc, Carbon Electrodes and MnO2 from a Lantern Battery

2. Make MnSO4 from MnO2 [2 ways]