HELP Required on Science Demos! - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: September 29, 2021, 05:07:07 am
content: I've been roped into giving a 1hr online science demo to a bunch of 10-11yo's about forces, energy and electricity next ThursdayThis is an early guideline.Haven't really though about it yet, and don't know what electricity component they want yet.My first thought was a demo of a neodymium magnet down a copper pipe to show how it slows down. This demonstrates gravity, magnetism and electricy all in one.Another though as the 2-G tipover effect in crystals, and a demo of how tipping a crystal oscillator over applies gravitational force to the crystal and changes the frequency. Easy demo I've done before.The other more physics type stuffI had a fleeting thought about using my thermal camera to somehow show a temperature change when I apply a force (like squeezing?) to somthing?Maybe a demo of electrostatic force pushing something?Bending water with electrostatics?Any ideas appreciated!Obviously they have to be realtively simple and effective, and doable by next thursday.Thanks.

author: EEVblog
author_rank: Unknown
timestamp: September 29, 2021, 05:40:02 am
content: Turns out it's a multi part series!Forces, then transformation of energy, then electricity.So the one next week is just forces as per the sylabus.

author: antenna
author_rank: Frequent Contributor
timestamp: September 29, 2021, 06:00:27 am
content: Quote from: EEVblog on September 29, 2021, 05:07:07 am-Rubber bands get hot when stretched and cool when relaxed.-Kelvin Water Dropper?-Electroscope(like a Kearny Fallout Meter)?For a non-contact force, it would be cool to find a radiometer and a laser by next thursday.

author: daqq
author_rank: Super Contributor
timestamp: September 29, 2021, 07:57:30 am
content: An improvised single stage/multistage coilgun is something the kids might enjoy? Have the 'projectile' hit a light object then a heavy object and measure how far the other object travels? Play around with the voltage/energy in the capacitor? Don't overdo it though, people like their eyesYou will demonstrate how by means of magnetism and inductors electrical energy is transformed into kinetic energy and movement and how the same amount of energy will have a different effect on an object depending on its mass.

author: jpanhalt
author_rank: Super Contributor
timestamp: September 29, 2021, 10:11:01 am
content: Transformers and turns ratios.Buoyancy in air -- large, thin trash/dry cleaning bags filled with hot air and/or whatever you can find.

author: GlennSprigg
author_rank: Super Contributor
timestamp: September 29, 2021, 11:02:08 am
content: Why don't you check out the plethora of "julius sumner miller" youtube videos, aimed at kids!!He was a wizz, at educationally maintaining interest in kids!!

author: EEVblog
author_rank: Unknown
timestamp: September 29, 2021, 12:10:30 pm
content: Quote from: antenna on September 29, 2021, 06:00:27 amKelvin water dropper has been on my video list for the last month. Thunderf00t and I were discussing it recently actually.Yeah I was thinking of a stretchy material that heats up when stretched or compressed.

author: EEVblog
author_rank: Unknown
timestamp: September 29, 2021, 12:11:07 pm
content: Quote from: GlennSprigg on September 29, 2021, 11:02:08 amI've read his autobiography actually!

author: EEVblog
author_rank: Unknown
timestamp: September 29, 2021, 12:12:15 pm
content: Quote from: daqq on September 29, 2021, 07:57:30 amHome schooling for a bit longer, so this will be online zoom thingy.

author: PlainName
author_rank: Super Contributor
timestamp: September 29, 2021, 12:20:07 pm
content: QuoteI know the syllabus has changed since you posted, but in principle it's still relevant.This would be a cool thing done well, but just showing the magnet not falling down is simply a magic trick and doesn't teach or lead to anything. You would need to first demonstrate magnetism (and particularly that magnet), then inducing a current (perhaps shoving that magnet through a coil to light abuldLED), and then perhaps the reverse (moving that magnet by closing a switch). The idea is that the parts need to be knowable so you can put them all together in the final demo and it makes sense.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 29, 2021, 12:43:01 pm
content: The usual way to show force is with the extension of a spring. The simplest (at least at the beginner level - no longer for the experts) force is usualy gravity. So use something like equalt weight parts that sum up.Learning often works well with emotion and a technical strong emotion is something failing. A horizontally span string loaded in the center up to failure could be interresting. It fails relatively early because of the addition of forces as a vector. This can be shown with 3 springs in 3 directions.

author: CJay
author_rank: Super Contributor
timestamp: September 29, 2021, 01:25:24 pm
content: Cool example of non contact force is the magnetic levitation toys, the floating globe things, you can also introduce electricity with an electromagnet and disrupt the levitating toy.To demonstrate the heating effect, you could monitor the electromagnet with your thermal camera, conveniently monitoring the current/voltage

author: Kasper
author_rank: Frequent Contributor
timestamp: September 29, 2021, 04:05:33 pm
content: Combine a function generator, speaker and oscilloscope. Bonus points if it's a big, unenclosed speaker that is cheap so they can see it move and touch it.Extra options:Add an amp and adjustable filterReplace function generator with music or microphoneAdd rectifier and LEDs, maybe even use LEDs in the rectifierUse thermal camera and see if you can heat the speaker upThe first part was my first lab in college and one of very few labs that I remember from 2 years in college and 3 years in uni.

author: armandine2
author_rank: Frequent Contributor
timestamp: September 29, 2021, 05:21:07 pm
content: I have some experience of teaching this age range and I would start off with the assumption that "force(s)" are not words that have yet made a place in their vocabulary and definitely not in their present understanding - and except for a minority of pupils who will have an inkling of your lecture the majority will be more confused after your talk than before it. There is something called the "spiral curriculum" which rationalizes this process of teaching different age levels. The idea is that you pitch it (your content) in terms and ways which resonate with the audience. You should not be illogical but admit that the content you give would not satisfy you.]ed for spag[

author: EEVblog
author_rank: Unknown
timestamp: October 04, 2021, 07:14:10 am
content: I put this together to see how it would all work:

author: PlainName
author_rank: Super Contributor
timestamp: October 04, 2021, 01:07:36 pm
content: Small point: in the elastic band demo I think it would have been a bit better to hold the left side (that is, the bit that stays under the camera) with something that isn't your hand. Reason being that your hand warms it up, and when you stretch it you're pulling that warmed part into view so it's not obvious whether the demonstrated heat is from your hand or stretching. If it were pure stretching you'd expect a more or less even spread, whereas it is definitely at body temperature close to your finger. Maybe it would be sufficient to either ack that, or move that hand out of view so only the middle of the elastic band is shown.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 04, 2021, 03:20:37 pm
content: The effect of the crystal frequency changing is especially large with the tuning fork types (e.g. 32 kHz). There is explaination is also relatively simple: when pointing down the arms will see the normal elastic restoring force and additionally a resoring force like for a pendulum. When pointing up, the grativity part makes the position less stable and lowers the frequency.The more disc like quartz crystalls are less susceptible and the temperature in the crystal oven can have an effect too.If the watch is used a tuning fork type 32 kHz crstal (not all do, some also use 4.192.... MHz more disc type), chances are if would be in the horizonal when the watch points up or down, so not much change in that special case.AFAIK they used such systems with 2 relatively large (to get a stronger effect) tuning fork type crystalls to acutally measure the strenght of the gravitational field. AFAIK this was used as an additional navigation help for nuclear submarines.The point of elastic collision is not wether all the momentum is transfered, but it is about conserving the energy or not.The 2 cars on the rail have quite a lot of friction. So good to show the more static part, but not that great for the collisions.

author: DrG
author_rank: Super Contributor
timestamp: October 04, 2021, 03:51:09 pm
content: I watched the whole video and I think it is good, but that may have little bearing on a viewing by a 10-11 year. Additionally, there is no standard 10-11 year old, so one aspect is whether you simply want to “reach” as many as possible (lowest common denominator) or concentrate on feeding those that want more of that material. I think that it is a legitimate differentiation and it is difficult to do both.We all show some interest in seeing something that we can’t “normally” see because it is essentially mind-expanding. The IR cam does that beautifully. It was mentioned that you might not hold the rubber band in your hand because of the visual heat transfer. You could work that to your advantage by using tongs first and then your hands. After which, the demonstration can proceed as you have done.The magnets would benefit by a similar visualization (I am sure you know how better than me,https://www.coolmagnetman.com/magvisual.htm).So, when you get to gravity, the effect on quartz oscillators requires a transition, and it is difficult, but the demonstration works well I think. The challenge is in not going too far explaining an oscillator and time keeping and rubidium. Maybe the way you are doing it is fine – I am thinking that you will get declining attention/understanding at that point, but that may not be a bad thing – feeding those that want more of that material …..i.e., sometimes it is difficult to “see” forces but we can tell they are there….A small point is consistency of language. At ~ 5:20 you say “the energy is removed” and I wonder about how language-careful you have to be and which words they hang on.I have given many presentations to many adults and when you have a fixed amount of time and detailed information, I always had a sinking feeling about lying, not to be deceptive, but because the alternative is to take up all the time with prerequisite detailed explanations. My point is to somehow, streamline and simplify oscillators and frequency. Sitting here, drinking coffee, I considered a metronome as an introduction – but I don’t know if that would work.Lest anyone thinks I am being too critical, let me state outright that if you did not change anything, the presentation has value and is better than many I had as a 10-11 year old (and yes, I do remember).

author: EEVblog
author_rank: Unknown
timestamp: October 05, 2021, 12:51:29 am
content: Quote from: dunkemhigh on October 04, 2021, 01:07:36 pmYep, realised that. Will change it on the day.

author: RJSV
author_rank: Super Contributor
timestamp: October 08, 2021, 04:50:20 am
content: I'm thinking 'EXPLOSIONS...REALLY BIG'..Uh maybe...For, tellem you have a 'couple explosions, maybe', as kids really appreciate you have a fun deal, making safe distance from audience.A really good smooth-talker can also get audience involved, friendly: "Now, remember to hold your ears, those of you near."OR: ,"It's only a frozen nitrogen shrink-tube, shatters when warms back up..."Forces, you want a 'teeter-todder' lever, DEMO the classic 'weight times lever arm' equivalencies.Also, some 'air' related force per square inch.At 14 pounds, per SQ inch, calculate the AIR PRESSURE exerted on one side of a normal sized door.

author: Circlotron
author_rank: Super Contributor
timestamp: October 08, 2021, 05:12:17 am
content: Quote from: EEVblog on September 29, 2021, 05:07:07 amThat's a fascinating demo, but probably only to an audience that already knows what a crystal oscillator is / does / is used for. For those that aren't familiar with one I think it would be lost on them.--------Gyroscopic forces are pretty cool. Get a bicycle wheel and spin it up and have some sort of extended axle with handles and show how it resists being tilted. Discuss how this helps keep a bicycle upright, and if for example the bicycle is leant to the right the revolving front wheel also turns to the right so you can steer no-hands.

author: mathsquid
author_rank: Frequent Contributor
timestamp: October 08, 2021, 08:31:13 pm
content: There’s a cool and easy demo you can where you drop two stacked balls. If the lower ball is larger than the upper one, it will i part more energy to it. It works well with a basketball and a tennis or racquetball ball. You could do it with two tennis balls and then with a basketball and tennis ball and show the difference.Here’s a video. (Skip to about 1:10)https://youtu.be/yhTz_6NFmV0

author: EEVblog
author_rank: Unknown
timestamp: October 08, 2021, 11:53:29 pm
content: Quote from: Circlotron on October 08, 2021, 05:12:17 amMy live demo turned out quite well, and it seems that the crystal oscillator one was the most fascinating to them and drew the most questions. I think I blew some minds with itHere is how that part went down. There were more question but I cut them down.

author: Circlotron
author_rank: Super Contributor
timestamp: October 09, 2021, 01:42:26 am
content: Quote from: EEVblog on October 08, 2021, 11:53:29 pmIf you could show how time goes slower in a gravity well, that would be cool.

author: PlainName
author_rank: Super Contributor
timestamp: October 09, 2021, 10:01:14 am
content: ExcellentQuoteShame, but one way to beat the population explosion, I guess.

author: sandalcandal
author_rank: Unknown
timestamp: October 09, 2021, 10:53:31 am
content: You should post more videos like this to the main channel. You'll be swimming in views

author: Kleinstein
author_rank: Super Contributor
timestamp: October 09, 2021, 11:40:06 am
content: The frequency shift is quite small for the disc shaped crystalls, but it is quite a bit larger for the 32 kHz tunig fork types. Chances are one would not need such a high quality counter. The change may reach the 1 ppm range and thus measurable in a much simpler setup.The observed change with the counter was a bit slow - so not sure if the is atually the direct gravity effect on the crystal. It could be as well be a thermal effect on the quarz oven. Turning the oven upside down can upset the temperature, both as a transient and static.

author: EEVblog
author_rank: Unknown
timestamp: October 12, 2021, 02:44:01 am
content: Quote from: sandalcandal on October 09, 2021, 10:53:31 amFrom the number of Youtube videos our kids get sent to watch from teachers, I can believe it!

author: EEVblog
author_rank: Unknown
timestamp: October 12, 2021, 02:46:18 am
content: Quote from: Kleinstein on October 09, 2021, 11:40:06 amThe slow update was due a fixed 1/sec sample rate required to get the extra digits resolution.

author: RJSV
author_rank: Super Contributor
timestamp: October 13, 2021, 12:48:39 am
content: Thinking a while, what would be popular, (although not everyone in class gets curiousity), is that THERMAL IMAGE IR camera. Possibly because that's usually a 'hidden' part. Kids would ponder, how something could be there, influencing how warm something gets, yet radiation always has that unseen quality.The IR camera makes it clear, radiation travels like 'light' does...surprise: Light IS radiation.Plus, you can do lots of side activities, using an IR camera on your experiment bench.