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My pleasure: Filmed on 20/04/2018 and published on 26/07/2018 in England, UK Hope that helps.

Thank you so much. Hopefully I can learn much from you.

My pleasure and good luck with the project.

Thanks. Yes it is a very interesting problem and it was fun trying to show it this way. Thanks for sharing your thoughts!

Glad you liked it!

Yes, David, it is 60. It is a high composite number and the first one out of the 100 switches to have 12 factors. Then 72 and then 84, 90, 96 I believe.

1 is obviously not correct, because that is only ever switched on the first turn (because 1 is not divisible by anything except 1).

Yes, it has only one factor.

Something a bit different this time Mark!

Good guess! Note that some are divisible by 3 (for example) so cannot be prime numbers! Thanks for watching!

​@@AnthonyFrancisJones I guess my comment was confusing. The first line was my first guess as you requested. I then editted the comment to add my new understanding. Anyway, interesting how that turned out.

Excellent and you did exactly what I did which was worked away at different patterns until one seemed to emerge the winner! Thanks for your comments as ever!

@@Rouverius By the way, I meant to put up any picture for the thumbnail but it turned out I put up a rather 'relevant' one by accident! Glad you still watched the video though!

Leonardt, thanks very much for this. Yes you are totally right. I am just sharing some of my ideas at builds to encourage those that are beginners to go that little bit further and think about what they could design and build as a device without worrying too much about its final functionality. As well to build something without resorting to the likes of Arduinos and code to solve problems. As a kid I knew what most of the chips did but did not really visualise how to string them together to do things. Building like I show now helps to get this modular idea across. It's just a bit of fun really! You understand that fully! I do, however, value all the wonderful comments I have had including constructive criticism and how one could improve the designs. They are really interesting too. Thanks for sharing your experiences. Always great to hear other people's stories and experiences. That's what makes it all worthwhile!

Thanks for the excellent comment (more than just a comment but that's what RUclips call them!) Yes, agreed, this is just a bit of a fun project as you say. As you say the 15% error could come from so many places, from temp changes to component tolerances (though I would be surprised if these change that much - rather being fixed in value). I think the main thing is down to my calibration of the LDR part of the circuit. It only points in one direction and through the window at that! With a clear sky I notice our solar panels are never as effective as when there is scattered light! The 555 calibration was only done over a short time period too. I am tempted to adjust the trim pot to see if I can get a better setting but I guess as soon as I knock the LDR board out of place it will all change again! Just a bit of fun but I enjoyed the design and build! Now, I really should buy a caesium clock... Well, I'm not Curious Marc!

Thanks Stephen. You should go. We feel that we are really lucky to have such a beautiful town close by. There are even rickshaw bikes that do free town tours now! Glad you liked the video and let us know if you end up visiting. BTW you can do tours of the prison too, another of Thomas Telford's builds!

Yes! Good point! You have got me thinking... should I build one that measures the depth of water in my rain gauge in binary. Might get more use!

Yes, I think the 555 timer at least comes out of a box of ones I had as a teenager! I did think of putting a decoder on it to show the values in decimal too on seven segment displays but I felt I wanted to keep this binary. Using an LED as a light sensor is a good application and one that not everyone is aware of. I have been meaning to do a video on the C-S solar recorder for a while. You can use a piece of film and a pinhole camera shoebox or a simple convex lens, toilet roll tube and paper. Obviously I would want students to be aware of the risks of working with bright sunlight. Do you remember that lady's house that burnt down, was it last year, with a glass item causing the curtains to go on fire! Always good to hear from you and hope you enjoy my next ones!

Wow! That sounds like you have a fantastic and well sorted set up! I have a few Raaco type cabinets mainly for electrical connectors (most of which I will never use such as MUSA etc!) and bolts of all sizes. As a teacher I love Gratnalls' trays. Brilliant in every way and I still use single ones for keeping project parts together. Currently I just don't have the space for a good pillar drill, lathe etc. Wish I did but I kind of like my less technical way of doing things! What are we to do with all this stuff when our time is up. My partner would have no idea. Just hope my son takes and interest! As far as the steel rule goes. I have had it for over 20 years. It does not have a name on it but I think we had sets of them in the school's DT department if I remember rightly. I had lots of wooden metre rules in the lab too and some of them were ridiculously badly marked. The kids were always struggling to read them correctly. Shame comments do not allow the posting of photos as it would be interesting to share ideas and workshop layouts. BTW seems to be far from CAVOK here and permanently 8 Oktas! Good to hear from you as ever and do keep the comments coming!

Thanks Mark! Useless at the moment as our summer weather is so poor!!

Yes, you are absolutely right. There are at least two approaches and I think there is a time and a place for each. I always feel it provides some inner understanding if done well, for example Force x Velocity being in units of Power - not obvious a very first sight to a beginner! (BTW I am constantly annoyed by adverts for phone power bank batteries on the internet offering batteries with 90000000mah ratings! What is going on there??! I must get one of these!!)

@@AnthonyFrancisJones At school, in the days of Dymo tape, friends and I annotated a PP9: "Beware: 9000 mV". It just shows how the humour threshold shifts with maturity.

Excellent! Yes, the days of sending students to get a 'long weight' or 'some resistance' from the technician! On a more serious note I remember the problems the general public had dealing with the units after the Chernobyl disaster or even the 'massive' energy of the LHC. 14,000,000,000,000eV ! BTW what do you feel about commas as order of magnitude separators - I note my overseas pupils all use full stops. It gets very confusing!

Agreed! It is good if you can actually test something out and get a feel for it like in my experiments. I set myself a challenge of doing an experiment or demo every single lesson. Got harder with time and pressure! Thanks for watching and taking the time to comment too!

@@AnthonyFrancisJones Actually thank you for taking the time of making these videos and also replying! Cheers from Argentina!

@@cocusar My pleasure and it is always good to hear where people are watching from!

Thank you. That's very kind of you and I am pleased that a teacher got your interest going and unlocked your potential! Always great to hear stories like that. Glad you liked this rather unusual video. I had fun making it! Hope you enjoy some of the others too. I try to do something a bit different from all the other (larger) channels and there is more to come! Look forward to hearing how you get on.

Thanks - yes, they won't let you down when batteries fail! Good idea, I must do one on vernier calipers too. I had a huge school class demo slide rule a while ago and when we moved I chucked it out. As with most things I have thrown out, I wish I had kept it! As ever thanks for watching and your support of the channel.

@@AnthonyFrancisJones Thanks, sir is it possible for you to do a demo on potentiometer and metre bridge and how to compare emf of two cells or determine internal resistance of a cell. I checked the slide rule from the internet, it's really a cool device!

Yes, those are real old-school but important experiments. I will have to have a go at some stage. The Wheatstone Bridge is such an important device to understand before doing other such experiments. Keep studying hard!

Thanks, that's very kind of you and glad you liked it! Thanks for watching too!

Good question. So this is a static effect so if you were to do it quickly the acceleration might well make it fall off in the same way as if you suddenly moved it sideways. However, if all the movements are done slowly/gently then you can move it up and the centre of gravity does not change its position with respect to the perch (I think I demonstrate this) and it will remain balanced. Then, if you tilt it, as long as there is a bit of perch in contact with the bird's beak and there is enough friction it will still be supported as the centre has still not moved with respect to the perch. However, friction will limit the angle that it can be tipped through and of course if at 90 degrees there will be no actual support under the beak at all so it will fall. Hope that makes sense and helps. Good question!

@@AnthonyFrancisJones Thanks teacher i understand fully!

@@certifiedmunch.876 Excellent - hope your studies continue to go well!

Excellent! The main idea is to realise that there is constructive and destructive interference happening as incoming and outgoing wavefronts meet. Getting the hang of where there is a 180 degree phase change is not easy and if the reflection is off the top or bottom surface of the oil but I hope you get the general idea from this simplified explanation. Have you seen this one too using a DVD or CD? ruclips.net/video/GcKttihc8ts/видео.html Good luck with your studies!

Yes. they do as they are directly connected to the + and - of the power supply all of the time. There will of course be a tiny fluctuation when the ball touches but nothing that one would notice at all. It would be a different matter if a huge charge was put on plates and then they were disconnected and the experiment run again. The ball shuttling would have the effect of slowly passing opposite charge to each plate and neutralising them bit by bit! Good question and thanks for watching!

@@AnthonyFrancisJones thank u for ur answer. What is the name of that HV name please?

@@pintchigawza6496 It is a 5kV school (low current) EHT power supply. www.science2education.co.uk/product/power-supply-units/EL10370 However, you must know what you are doing when using these to keep safe.

@@AnthonyFrancisJones thanks

Thanks. It is an unusual piece of apparatus isn't it! I did not delete the comment but when you comment there are two buttons very close together 'Cancel' and 'Reply'. I have typed a long comment before and hit the Cancel button by mistake and lost it all! I will have to look at the Slow Mo Guys video - thanks for the tip and for watching and taking the time to comment a second time!

Thanks again Tony. Filmed a while ago but such an interesting odd piece of apparatus!

Great! I went round in circles until I got the bulb out so just had to share how to do it! Glad it helped you!

Do you mean the large horseshoe magnet?

Good question and I hope this answers this. Remembering that each core is used as one bit of data and it works as a transformer, you do need an AC signal to make it work. I use the transistors here to switch this AC (square wave) on and off depending on whether it is a lit or not lit LED that is needed. They LEDs or the cores cannot be directly driven from the 7 segment display chip if that makes sense. That is why there are two 555 timers - one to scroll the digits and one to proved the cores' high frequency signal that gets switched on and off. Hope that helps and thanks for asking!

Thanks Neil! Yes, those gates! Lots of getting in and out. Not very common on public roads anymore but at least the handbrake held! Thanks for watching and taking the time to comment too!

@@AnthonyFrancisJones have you watched the gods must be crazy the start of the show is a series 1 it’s hilarious Take care and safe travels N

No. But I know I must!

Thanks and great to hear from you! Yes, this was an interesting one to make. The Challenger connection is facinating - I think I forgot to make it clear that the issue with the SRBs caused a flame front to leak out burning out the O rings but I guess that was obvious! I think it is a great bit of maths too! Must do solids of constant width at some stage. Working on a few maths based ones at the moment which I think you will enjoy. Hope to get them sorted soon!

Thanks Alice! Yes it is so simple when you know but I spent ages fiddling about struggling with it! Hope you are successful!

Thanks Eugene. I made this ages ago and was quite pleased with it but it never generated much interest. Good that you enjoyed it!

Thanks again Eugene and for supporting this small channel. Hope you enjoy some of the other videos too!

Thanks Poma. Not quite Christmas but a nice experiment none the less! I like the videos you have done with fruit and LEDs!

Look forward to hearing more...!

Thanks! Glad you liked it! Yes, my thoughts go in phases and it's gears etc. at the moment. Now, here is an interesting idea that I have not seen done before: what I want to do is put a belt all the way round it so it becomes a level but odd shaped rotor caterpillar track. I think that would be fun and very counter intuitive! Sounds like something Colin Firze would build (with a massive engine on it!).

Thanks Jakob. Guess you mean my son rather than me!

Yes, not what I expected at all but I learnt something from them that one must not forget fluid dynamic effects in blood flow too! Physics is everywhere!

Pleasure! Glad you liked it. Rather niche but I thought it is something that people should see regardless! Hope you enjoy some of the other videos too. Do let me know!

Thanks Muhammad. Is there anything more technical that you would like me to explain or to add? If so I can add it to the pinned comments. I made this video as a general science example so it was not meant to be too technical but I get your point - there is so much more one can say about strobes and strobing effects! Thanks for watching and taking the time to comment.

@@AnthonyFrancisJones How rotational speed of the fan can be matched with the frequency of light, by determining the amount of time the fan rotates to it's position and having that frequency in the light etc, overral a little more depth on technical side.

@@MuhammadAnas_Official Thanks, that's a good idea and would allow for the introduction to angular velocity ideas. I could do the experiment with a swinging pendulum too to show the similarities of linear (small amplitude) oscillations to circular motion. I guess I only have under an hour in my lunch break and no script so they are a bit quick and simplified but I do really value your input. It is always great to get suggestions even for other videos such as the Tennis Racket Effect or the Halbach Effect which were both suggested by different subscribers. There is so much interesting physics out there!

Pleasure Mark and thanks for supporting the channel as ever!

Excellent! I have a few Wilescos and a few Mamods - love all of them!

Yes, I remember that sphere when it was discussed in Physics World a few years ago. Not quite that close indeed! I really would not want to cut it in half but would be interesting to see what it looks like. Ultrasound would just produce an mess of an image I think. Adam Savage did a good job with the water jet cutting ruclips.net/video/onZDAKJq6z4/видео.html I really feel that, whilst there must be lots of voids, dirt/oxide etc. the layers may well have got close enough to form metallic bonds. It was a fun project regardless and thanks as ever for your interesting observations. Do keep them coming!