Waste less time on Facebook — follow Brilliant.
×

MIT Graduates Struggle to Light a Bulb with a Battery and Wire

The video: Scandalous!

I saw this video going around of engineering students at their graduation from MIT who were unable to power a light bulb using a battery and a single wire:

It is surprising that the engineers would have trouble rigging up the circuit. Let's take a look at the problem and see what this episode can teach us about effective learning.

\[ \] \[ \]

The solution: Back to the basics of electricity

A conventional lightbulb has two terminals—one at the base and another at the threads of the bulb. If these two terminals are kept at differing voltages, current will flow across the bulb, causing the filament to glow.

The obvious way to close the circuit and light the bulb is to use two wires:

  • connect a wire between one terminal of the battery and the rim of the light bulb
  • and a second wire between the other terminal of the battery and the base of the bulb.

While the setup with one wire appears to be different, it is actually the same. We can see this by drawing a diagram.

\[ \] \[ \]

Case 1: Closing the circuit with two wires

Consider the conventional circuit with two wires

Let’s ask ourselves a simple question: what is a wire? The answer is: a tool to connect two components of an electrical circuit. This is all the insight we need to close the circuit with one wire. \[ \] \[ \]

Case 2: Closing the circuit with one wire

Looking at the battery and the light bulb, it's clear that we can touch one of the terminals of the battery directly to the threads of the bulb.

For instance, by touching the positive terminal of the battery to the thread of the bulb, we put the threads at the same potential as the positive terminal. If we now use the wire to connect the terminal at the base of the bulb to the negative terminal of the battery, the circuit will close, with a sustained voltage across the terminals of the bulb that's equal to the voltage of the battery—let there be light!

Thus, we can eliminate one of the wires without incident.

You may have noticed this isn't the only way to close the circuit. In fact, there are three other arrangements that will work. While the bulb requires a voltage across its terminals, it doesn't care about the polarity.

So, we could also do the following:

The simple lesson is: if there's a way to make two circuit components touch without using a wire, we don't need to.

\[ \] \[ \]

A hazard of higher learning: Losing the basics

Those students probably all knew how lightbulbs, circuits, and batteries worked. However, they also probably spent the last several years of college in upper division classes that focused on abstraction and theory. When confronted with the basics, they no longer recognized where the lightbulb and the battery fit into their skill set and knowledge base. This is not a problem unique to MIT or elite academia. Losing track of the basics is an innate hazard of learning a lot very quickly.

Chief Happiness Officer Zorro consults with Pete.

Chief Happiness Officer Zorro consults with Pete.

\[ \] \[ \]

Conclusion: Develop a firm understanding of simple cases

In any field that you find yourself in, you can protect yourself from a future light bulb + battery moment by laying your foundational knowledge in the firm understanding of simple cases. If you have a sound understanding of the fundamentals in your discipline, you will always be able to derive more sophisticated ideas from the basics. Conversely, it's extremely hard to rediscover the fundamentals from merely remembering the wealth of fancy results of your field of study. In other words, when you get lost… go back to the basics.

Want more like this? Check out the Physics of the Everyday course.

Note by Josh Silverman
3 months, 2 weeks ago

No vote yet
1 vote

Comments

Sort by:

Top Newest

Apparently, these Harvard grads haven't ever taken a flashlight apart. I mean, how many times have I had to take apart a flashlight because the battery wasn't making a good connection with the bottom of the bulb?

Then again, maybe they don't make flashlights like that any more. Maybe it's all done with Wi-Fi. Michael Mendrin · 3 months, 1 week ago

Log in to reply

@Michael Mendrin I didn't think of this. The flashlight definitely raises the stakes. Josh Silverman Staff · 3 months, 1 week ago

Log in to reply

It is vital that there be practical/vocational training for students. I am from Afghanistan and most 5 year old kids there would be able to achieve this because they have played around with batteries and bulbs. I remember a Big Bang Theory episode where Howard was asked if he knew about internal combustion engines and he said something along the lines of "Yeah, I am an Engineer" but couldn't fix one. I would think practical portion of the field is just as important as the theory when teaching! Yasir Soltani · 3 months, 2 weeks ago

Log in to reply

Unbelievable. Really. Déo Melgaço · 3 months, 2 weeks ago

Log in to reply

isn't that ur dog sir :) Hiroto Kun · 1 month, 2 weeks ago

Log in to reply

@Hiroto Kun This is possible. Josh Silverman Staff · 1 month, 2 weeks ago

Log in to reply

scary. Joel Pokladnik · 3 months, 2 weeks ago

Log in to reply

Wow. Interesting !! Ifrah Ghauri · 16 hours ago

Log in to reply

×

Problem Loading...

Note Loading...

Set Loading...