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Note that I will actually have to conduct the experiment in regular laboratory conditions. Basically I want to find an experiment where I do something with ferrofluid, a liquid full of tiny magnetic particles that can change for example the shape of still ferrofluid or its flowing speed (and flowing direction even, if I'm guessing right?) Anyway, the experiment must prove (or suggest the reliability of a theory on fluids/ferrofluid) a physical property of ferrofluid. An example experiment would be such where I would have ferrofluid and I use an electromagnet to affect the flowing speed of the liquid by altering the force it applies to the ferrofluid (a reaction in terms of flowing speed of the ferrofluid due to force being applied to its magnetic part that is, the submerged tiny magnetic particles). THE PROBLEM is that I need to do something that I can measure which is really hard because magnetic field is not strictly to one direction in practice. Can someone help me find an experiment on ferrofluid that I could write my 4000 word essay of physics on? Thank you so much in advance - this is really really hard.
I have never studied ferrofluids. I've just watched them in action on YouTube. I have like two ideas, and I really don't mind if you shoot them down. That's brainstorming! And I know next to nothing about these fluids. 1. Try some idea with flowing, like you were saying. If you have a strong enough magnet or electromagnet, you can simplify it to a point source or solenoid from a distance. You can calculate the expected deviation of acceleration/average velocity/time taken to travel a distance as compared to how the fluid flows without the presence of the magnetic field. Hopefully you have access to computer software and hardware to measure the fluid's position - like a laser-reciever gate, or radar/sonar that works with a computer. Radar/sonar might work if the fluid is detectable while the incline isn't... Laser-reciever gates will mark when the fluid hits a certain point on the incline, so that you can plot the time vs distance with multiple gates, or just know time spent on the incline to the point where the laser-reciver is. The most important part is calculating theoretical results that line up with the measured results. And I'm not the guy to talk about standard deviation, but make sure it's in there... 2. POSSIBLY TOO COMPLEX: If you have access to hardware and software to track movement, you can have a ferrofluid freefall from or to a powerfull magnet (probably an electromagnet whose magnetic field can be simplified into that of a solenoid) and evaluate the resulting difference in acceleration or average velocity or time spent in freefall. You'll have to compare that test to dropping the ferrofluid without the presense of a non-negligable magnetic field. Like, make sure you don't have your handy-dandy supermagnets in your pocket. Hopefully the fluid's shape won't change, because then you might need to show that the change in ait resistance is negligable. This is like the ramp, with harder measurements (because the fluid will move fast, maybe too fast for hardware), no factor of friction on the incline (if applicable anyway), and a factor of gravity's full force. I don't know what equations you have to work with, if any. Sorry my ability to help you is limited! Good luck!
If you have any way of calculating what the shape of the ferrofluid should be on a thin plate over a magnet, that would be direct... Change some variables.
Or maybe have a magnet on a thin plate and have the fluid underneath, and calculate how strong the force holding the plate up is. Then show that your calculation is correct by adding weight to the plate until it crashes down into a bag or something. But I don't know how you would go about calculating that.
First of all many thanks for taking the time to answer with such detailed ideas. As for what you suggested in your first model you said: "You can calculate the expected deviation of acceleration/average velocity/time taken to travel a distance as compared to how the fluid flows without the presence of the magnetic field.". In practice how could I make this happen? Say, we have for example a long-ish thin open glass tube tilted 45 degrees and through this flows ferrofluid with a certain velocity (neglecting the troublesome aspects of keeping the ferrofluid input constant for now). Now, given the precise composition of the ferrofluid and the theoretical interaction between it and the walls of the open glass tube (giving rise to the slowing down of the fluid due to friction? I'm not even sure) we would come into a certain conclusion of the velocity of the fluid inside the tube. Here comes the tricky part. If you were to place a magnet anywhere in the system where the ferrofluid flow occurs, where would you place it and why if you were to find out how magnetic field force affects ferrofluid flow speed? Having said that how would the magnetic field generator be aligned with respect to the tube for us to be possible to have a theoretical model of the flow speed of the ferrofluid altered by magnetic fields of varying strengths? Additionally, I don't know if I'll be able to access hi-tech equipment so I was considering using the rate of change of mass of ferrofluid dripped down from the other end of the tube as the indication of frequency of flow of the ferrofluid at different points of time with respect to the initial step where ferrofluid is started to be poured down.What are your thoughts?
Do you use calculus? ** Before reading the bulk, consider a much more simple experiment, like having a container of ferrofluid on a scale, and measuring how much weight a magnet will take off. Just make sure the magnet doesn't affect the reading. Like, doesn't attract a metal scale's top, or alter the currents in the circuit. Maybe placing an object on the scale, and under the fluid, will increase the magnet's and fluid's distances from the scale. Like a stool (function-wise - I'm not suggest using a stool :P ). A container would make sure that the magnetic attraction to a part of the fluid will affect the entire mass by exerting a force on the container. And you would calculate the magnets effect on the ferrofluid as a function of the container's apparent weight. If you have to be accurate and you can use calculus, that's the real benefit of a simply shaped container of ferrofluid. Calculations using estimated shape of the fluid (or shape of the magnetic particle distribution) are easy with simple shapes. If the magnetic field generator can be accepted to be a distant source, then it will have different attractions to different parts of the container depending on distance. That will be calculated for your theory (the "expected" or "theoretical" results). Now, the rest. ** Some thoughts: (rough, still. I hope you can expand on them or continue to generate novel ideas!) measuring change in mass - To do this, you have to make sure you have a scale that will accurately record the weight accurately at time intervals? If you want to try this sort of setup, let me know! We could talk about that, then. The scale would have to be reasonably fast-acting, and the setup would have to minimize the impact of fluid hitting the scale, which would cause innaccurate readings. However, this is my opinion, while I'm being picky about accuracy. I don't know what requirements you have as you carry out this experiment. angle of tube - I would angle it so that the fluid would definately slide, but not so fast. That way, movement is slower and time measurements can be accurate more easily. possible beneficial change to free flowing fluid - if possible, a light, low friction, not magnetic, simply shaped container for the fluid will ease some calculations. Like maybe a small part of cheap plastic tubing with a creative seal (like tape). Or maybe an old film canister - though that might hold so much ferrofluid that the attraction would be less noticable at even a ideal angle of incline. And if you use a surface instead of a tube, you can maybe rig a little box. (Transparency sheets and super glue? I don't know...) Anyway, here are the benefits and downsides I see. 1. Friction. You can do a quick experiment to find the coefficients of static and kinetic frictions with a couple inclines; measure the weight of the container; and measure the weight of ferrofluid added. Then your force of friction can be calculated for your theory. Also, you'll know the weight for calculating its gravitational force along the incline, once you choose an incline angle. Also, the container's size on a flat surface doesn't have to be specific if its contact area with the surface is the same throughout the experiment - friction force is the same different amounts of contact surface area. 2. You can create this container ahead of time, maybe. Then the experiment will be easy. The container will be as easy to handle as a prop or a weight. 3. Theoretically calculating the force of a magnetic field on magnetic particles with movements that are mathmatically difficult to estimate is tough. Consider the shape of flowing liquid as it goes down a tube or incline. 4. This will prevent three problems I see. Firstly, you easily see when the fluid has travelled a certain distance. Secondly, the fluid is essentially one object - different parts of it would slide down a ramp differently. Thirdly, the release will be calculatable, unlike pooring or possible having some fluid leave a release contraption before or after the rest. 5. A sealed container is less messy (I hope). 6. In the case that the magnet is close to the fluid, it may be unacceptable to consider it a point source or solenoid (I don't know the requirements for this experiment). That's why a simple shape would be best. It's interaction with a field might be easier to calculate with formulas you find on the internet or on your own. measurement - Maybe you can use a camera that is prepared to capture or start at "t=0" when the fluid begins it's decent; and also make sure it can record to see when the fluid reaches a certain distance from it's starting point. Using a stopwatch manually might introduce considerable error, depending on how much your reaction time or "jumping the gun" differs from the time your measurement needs to happen, and how that difference will affect the computations you use it for. That's something to consider. I don't know what purpose you have to be doing this experiment, so I don't know what is "exact enough". If the fluid is slow-moving, maybe it will be easy to accurately measure with a stop watch, and such a measurement would be accepted by you professor, teacher, contest, or whatever else it may be. positioning of the magnetic field generator: where, why, and what orientation - I suggest the source be at one end of the ramp. The direction of attraction is CONSTANT! *celebrate* Constants are good in math (at least in my memory).
Oh! And maybe a free-flowing fluid's coefficients of friction are so low that friction is negligible on certain materials? I wouldn't know, and I don't know what assumptions are acceptable in this experiment. But I think some frequently used equations for fluids assume no friction. I would be only very minorly concerned with slowness due to the fluid flowing to the sides instead of straight down. In a small setup with simple measuring devices, I think it'd be negligible.
And orientation of a magnet or electromagent, in my opinion, should be whatever is easiest to calculate the force of the magnetic field on the fluid in different positions on the incline. Priority number two to consider when deciding on orientaion, in my opinion, is strongest flux possible down the incline, so the magnetic field's force is more affecting and thus more noticable and thus more measurable. With a bar magnet or solenoid, I believe your best option is pointing them down the ramp. For a ring, I think it would be best to look through the ring and .. picture time.|dw:1344579654170:dw| North and south can be changed. The three slanted lines are the inclines.|dw:1344580132867:dw|
I can't thank enough for the help and thoughts you've given out so far! Now to get right into it I really liked the simpler option you suggested. I'm bad at coming up with simple solutions to difficult problems (that being finding a simple experiment that features _ferrofluids_ :D) but I find your idea has a lot of potential. On a note to just respond to what you had asked; I have studied a course of basic calculus so I know the primary stuff. Now then, for the time being I'd like to elaborate the details of the simpler option of an experiment you suggested. The experiment setup is this: A container with ferrofluid is placed on top of an object. We don't yet know the dimensions of this object but it will elevate the ferrofluid's position from the scale itself to such extent that the maximum magnetic force exerted from a magnetic field generator [positioned somewhere above all the other objects; the scale, the elevating object and the ferrofluid container) will minimally, if at all, distort the reading on the scale. If the setup would have to be extremely high for no effect at all to occur between the magnetic field generator and the scale, then in that case we will write down the error made to the scale reading and take it into account into the results. After having decided how much magnetic force is needed and from what distance from ferrofluid - and with how big intervals is the magnetic force changed - to lift enough of ferrofluid's weight for good results, these values for the magnetic force that we need to apply are tested to find the possible error the magnetic field generator would generate on the scale. At this point we have a setup in which the magnetic field force magnitudes generated for example for 5 intervals are enough to sufficiently lift the ferrofluid and cause minimal error so that the results will be scientifically valid. This is the rough summary. "A container would make sure that the magnetic attraction to a part of the fluid will affect the entire mass by exerting a force on the container." This I don't get though - the container will be non-magnetic so that force will not be exerted on the container right? : p But the rest seems to make sense "And you would calculate the magnets effect on the ferrofluid as a function of the container's apparent weight. If you have to be accurate and you can use calculus, that's the real benefit of a simply shaped container of ferrofluid." Can you elaborate how this works in practice with some example values? "Calculations using estimated shape of the fluid (or shape of the magnetic particle distribution) are easy with simple shapes. If the magnetic field generator can be accepted to be a distant source, then it will have different attractions to different parts of the container depending on distance. That will be calculated for your theory (the "expected" or "theoretical" results)." With a Gauss meter I can find how many Teslas are from different displacements from the magnetic field generator, but along with this how do I find and use function of container's apparent weight and field line distribution to find the theoretical total weight that the magnetic field would lift? Ps. I sent you my e-mail as private msg in case you think it's easier to communicate that way, or we can just go on talking here if you prefer : p