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MoMoney$$$;)0) wrote: ↑February 25th, 2020, 6:14 pm I'm unsure of what to expect for a riegonals lab. Any suggestions of good lab practice. I've seen many types of lab's at several competitions like simple resistance of resistor, and voltage drop; but also things I've never heard of like an R2R ladder until the test (Solon). I just needed an opinion on what might be on a competitive regional test Lab section. Thanks!

Regionals are always so difficult to predict, but if I had to guess you'll probably get a breadboard with some mystery resistors, maybe a bridge circuit, but probably nothing as complicated as the R2R bridge you mentioned.

MoMoney$$$;)0) wrote: ↑February 25th, 2020, 6:14 pm I'm unsure of what to expect for a riegonals lab. Any suggestions of good lab practice. I've seen many types of lab's at several competitions like simple resistance of resistor, and voltage drop; but also things I've never heard of like an R2R ladder until the test (Solon). I just needed an opinion on what might be on a competitive regional test Lab section. Thanks!

Mystery resistor labs are really common, as are constructions that turn on lights (usually LEDs) in specific ways.

Fleshing out our team's preparation for regionals -- what is a typical "Equally Bright LED" hands-on task? Is it as complicated as looking up luminance/current specs for totally different LEDs, or generally something more like using different voltage supplies and matching the current so that similar LEDs light equally?

jmams wrote: ↑March 5th, 2020, 12:53 am Fleshing out our team's preparation for regionals -- what is a typical "Equally Bright LED" hands-on task? Is it as complicated as looking up luminance/current specs for totally different LEDs, or generally something more like using different voltage supplies and matching the current so that similar LEDs light equally?

This is usually really simple. Usually putting the 2 LEDs in parallel is all you need to do. You just have to match the current into each LED, like you said.

Krish2007 wrote: ↑March 5th, 2020, 3:49 pm

jmams wrote: ↑March 5th, 2020, 12:53 am Fleshing out our team's preparation for regionals -- what is a typical "Equally Bright LED" hands-on task? Is it as complicated as looking up luminance/current specs for totally different LEDs, or generally something more like using different voltage supplies and matching the current so that similar LEDs light equally?

This is usually really simple. Usually putting the 2 LEDs in parallel is all you need to do. You just have to match the current into each LED, like you said.

Adding on to this, since LEDs light up because of the current going through them, wouldn't you want to attach them in series because current throughout a series circuit is the same? While in a parallel circuit, the currents could be different if there are other resistors in the circuit. If an LED was driven by current then it would be attached in parallel, but I thought that you would have to attach the LEDs in series with each other because the current is what makes the LED light up. An LED lighting up is caused by electrons changing energy levels. This change occurs when current runs through the LED. Equal Current=Equally Bright LEDs. This was just my thought, I could be wrong though.

Krish2007 wrote: ↑March 5th, 2020, 3:49 pm

jmams wrote: ↑March 5th, 2020, 12:53 am Fleshing out our team's preparation for regionals -- what is a typical "Equally Bright LED" hands-on task? Is it as complicated as looking up luminance/current specs for totally different LEDs, or generally something more like using different voltage supplies and matching the current so that similar LEDs light equally?

This is usually really simple. Usually putting the 2 LEDs in parallel is all you need to do. You just have to match the current into each LED, like you said.

A short warning to never place LEDs in parallel unless each LED is in series with a resistor. The LEDs will burn out extremely quickly. Here's a good explanation for why.

For two identical LEDs, it wouldn't matter whether you place them in series or parallel (here, assuming "parallel" means "in series with one resistor per LED"). That's because, well, they're identical—you wouldn't be able to tell the difference. For LEDs with different operating characteristics, it's the power that determines the brightness, and power would depend on the IV curve for that particular LED. So, even ignoring how crazily wacky human brightness perception is, it'd be kind of hard to create two equally bright LEDs without knowing the individual specifications for the two LEDs

jmams: since you don't get Internet on the day of the event, the properties of each LED will probably be provided to you. Or even more likely, you'll simply be asked to use identical LEDs without having to worry about the LED's unique properties. After all, this is most feasible for the people running the event (but nothing I wrote here is a guarantee)

Good luck to you all!

UTF-8 U+6211 U+662F wrote: ↑September 5th, 2019, 12:23 pm

Pastaman202 wrote: ↑September 5th, 2019, 10:34 am The website allaboutcircuits.com is pretty good for beginners, although it isn’t a textbook. That website was a great introduction and relatively easy information, with a few sections that could be a bit more difficult.

I highly recommend this one for people that don't have a solid grasp of physics already. It would definitely be great for middle schoolers.

https://www.physicsclassroom.com/Physic ... it-Builder
https://universeandmore.com/crackthecircuit/

skylarrhaee wrote: ↑March 23rd, 2020, 6:50 am

UTF-8 U+6211 U+662F wrote: ↑September 5th, 2019, 12:23 pm

Pastaman202 wrote: ↑September 5th, 2019, 10:34 am The website allaboutcircuits.com is pretty good for beginners, although it isn’t a textbook. That website was a great introduction and relatively easy information, with a few sections that could be a bit more difficult.

I highly recommend this one for people that don't have a solid grasp of physics already. It would definitely be great for middle schoolers.

https://www.physicsclassroom.com/Physic ... it-Builder
https://universeandmore.com/crackthecircuit/

Good find; but it doesn't really grasp the event as a whole. You'd be better off for next year by reading an AP Physics 2 textbook, in the circuits section; or even reading the section on circuits in a college physics textbook.

MoMoney$$$;)0) wrote: ↑March 23rd, 2020, 9:13 am

skylarrhaee wrote: ↑March 23rd, 2020, 6:50 am

UTF-8 U+6211 U+662F wrote: ↑September 5th, 2019, 12:23 pm

I highly recommend this one for people that don't have a solid grasp of physics already. It would definitely be great for middle schoolers.

https://www.physicsclassroom.com/Physic ... it-Builder
https://universeandmore.com/crackthecircuit/

Good find; but it doesn't really grasp the event as a whole. You'd be better off for next year by reading an AP Physics 2 textbook, in the circuits section; or even reading the section on circuits in a college physics textbook.

if you want basic videos khan academy and organic chemistry tutor are good (especially for methods like node voltage)

imaditi wrote: ↑March 26th, 2020, 6:35 am

MoMoney$$$;)0) wrote: ↑March 23rd, 2020, 9:13 am

skylarrhaee wrote: ↑March 23rd, 2020, 6:50 am
https://www.physicsclassroom.com/Physic ... it-Builder
https://universeandmore.com/crackthecircuit/

Good find; but it doesn't really grasp the event as a whole. You'd be better off for next year by reading an AP Physics 2 textbook, in the circuits section; or even reading the section on circuits in a college physics textbook.

if you want basic videos khan academy and organic chemistry tutor are good (especially for methods like node voltage)

Yes, they generally give you the right idea as a whole, but to further grasp any and all topics that may show up on more advanced tests, you're better of studying a textbook then studying many articles on a topic. Video's as you said will help you visually grasp a topic as well.