01
Notice.
The back of the fridge is warm. That’s odd for a box that keeps things cold.
Everyday machines, opened up / Field guide
You use it.
But how does
it work?
Your fridge is warm at the back. Your kettle knows when to stop. There’s a good explanation hiding in plain sight.
Everyday things. Carefully explained.
Plate 011 — Induction stoveFig. A
01 / The latest explanation
The pan is the heater.
No flame. No glowing ring.
So where is the heat coming from?
HW–011 / Induction stove · 9:37
How Does a Stove Heat a Pan but Stay Cool?
Under the black glass there is no flame and no hot ring. We open a stove up to see where the heat comes from.
The glass can still be hot after cooking.
Fig. 011 — From copper coil to boiling waterPublished 31 October 2026
02 / How an explanation works
First, a puzzle.
Then, the pieces.
Knowing a part’s name is a start. Knowing what it will do next is better. Every video follows the same five steps.
02
Take a guess.
Does it make cold? Pause for a moment. What do you think?
03
Find the snag.
“Making cold” doesn’t explain those warm coils at the back.
04
Open it up.
Real thing. Cutaway. Clear diagram. Follow the heat from inside to outside.
05
Predict.
Leave the fridge door open. Will the room get cooler? Now you can work it out.
No screwdriver needed. We do the opening up.
03 / The complete library
Pick something
you thought you knew.
11 ordinary things.
11 reasons to look again.
11 explainers · pick a puzzle
9:37How Does a Stove Heat a Pan but Stay Cool?
Under the black glass there is no flame and no hot ring. We open a stove up to see where the heat comes from.
Open the explanation
9:25How Does a Lock Open for Only One Key?
Thousands of keys fit the slot, but only one turns the lock. We cut a lock in half to see how it checks each cut.
Open the explanation
9:25How Does a Ballpoint Pen Write on the First Try?
The tip is an open hole full of ink. We cut one open to see what keeps the ink in.
Open the explanation
10:07How Does a Thermos Keep Drinks Hot and Cold?
One flask does both jobs. We cut one open to see how it does it.
Open the explanation
9:05How Does a Toilet Flush Without a Pump?
A toilet with no pump still empties a whole bowl. We cut one in half to see what does the pulling.
Open the explanation
8:51How does an iron stay at the same heat?
The light is the clue. We open an iron up to see what is switching.
Open the explanation
7:42How does Teflon stay on the pan?
The answer starts under the coating, in the metal. We cut a pan open to see what holds the Teflon on.
Open the explanation
9:15How does a kettle know when to stop?
The kettle does not check the water. So what does it check? We open one up and find out.
Open the explanation
9:17Why your microwave freezes your Wi-Fi
The oven is not touching your phone, so why does it stop the video? We follow one video from the router to your phone.
Open the explanation
8:05Your fridge doesn't make cold
A fridge does not make cold. We turn one around to see what it does instead.
Open the explanation
6:25Why microwaved food is cold in the middle
The waves do not get far into your soup. So what carries the heat the rest of the way?
Open the explanation
04 / Notes from the field
A minute. An “oh.”
44 sec ↗An induction stove has no flame: the pan heats itself
Field note 01 / Short
44 sec ↗A key right on 4 of 5 cuts still won't open a lock
Field note 02 / Short
40 sec ↗A pen's tip is an open hole. Why doesn't it drip?
Field note 03 / Short
49 sec ↗A thermos doesn't know if your drink is hot or cold
Field note 04 / Short
36 sec ↗Pour a bucket into a toilet slowly. Nothing happens.
Field note 05 / Short
39 sec ↗Your iron's light keeps going off and on
Field note 06 / Short
43 sec ↗Your kettle never measures the water
Field note 07 / Short
33 sec ↗Nothing sticks to Teflon. So what holds it on?
Field note 08 / Short
45 sec ↗Full bars, slow Wi-Fi?
Field note 09 / Short
48 sec ↗How Wi-Fi writes bits on a wave
Field note 10 / Short
53 sec ↗Why the microwave freezes your Wi-Fi
Field note 11 / Short
43 sec ↗Why your fridge hums, stops and hums again
Field note 12 / Short
50 sec ↗Never cool your kitchen with an open fridge
Field note 13 / Short
49 sec ↗Your fridge doesn't make cold
Field note 14 / Short
45 sec ↗Why your microwave has a turntable
Field note 15 / Short
50 sec ↗Why microwaved leftovers are cold in the middle
Field note 16 / Short
54 sec ↗2.45 GHz is NOT water's resonant frequency
Field note 17 / Short17 small discoveries · Watch all Shorts →
05 / Still on the workbench
Coming next.
Two more things worth opening up.
Pressure cooker
Two pots are boiling, and one is about twenty degrees hotter. Why can a lid do that?
Zipper
Next in production: the zipper.
06 / A note from the workbench
Made with care.
And the lid off.
Hidden Workings is for anyone who has ever stared at an ordinary thing and wondered what’s going on inside.
The drawings are simple on purpose. The explanations take more work. Here’s what goes into them.
Curiosity is allowed.
Especially about the kettle.
Research before drawing.
We start with primary sources and check each claim. Every number has a source. You’ll find the references in each video’s description.
Simple pictures. Clear limits.
We write to a teaching plan, then draw and animate flat technical illustrations. Each description also says what we simplified on purpose.
A synthetic voice. Said plainly.
The narration uses Kokoro, a text-to-speech model. The research, teaching plan, drawings and animation are the work of Hidden Workings.
Good questions welcome.
Something doesn’t add up? Tell us in the video’s comments. A clear explanation should stand up to a closer look.
Try it at home
Start with what’s
in your house.
Make an observation.
Then see what explains it.
HW–011 / Induction stove
Induction stove
With the stove off, hold a fridge magnet to the bottom of each of your cold pans and see which ones stick.
See the explanation →HW–009 / Ballpoint pen
Ballpoint pen
Write with a cheap pen pointing up until the line fades. Then turn the pen over, scribble on scrap paper, and write again.
See the explanation →HW–010 / Door lock
Door lock
Lay two of your own house keys side by side, count the cuts, and find where they differ.
See the explanation →Why subscribe?
One machine.
A clearer picture.
- One everyday machine opened up at a time, in about ten minutes.
- Every number sourced. Each description says what we simplified.
- Shorts for a quick question between full explainers.
New explainers in production
See inside the
next machine.
Follow the cutaways from the real object to a clear diagram. Subscribe on YouTube to catch the next explanation.
Subscribe on YouTubeStay curious. We’ll bring the drawings.