How batteries work - Adam Jacobson

2,612,245 views ใƒป 2015-05-21

TED-Ed


ืื ื ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ืœืžื˜ื” ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ.

ืชืจื’ื•ื: Ido Dekkers ืขืจื™ื›ื”: Tal Dekkers
00:06
You probably know the feeling.
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ืืชื ื‘ื˜ื— ืžื›ื™ืจื™ื ืืช ื”ื”ืจื’ืฉื”.
00:08
Your phone utters its final plaintive "bleep"
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ื”ื˜ืœืคื•ืŸ ืฉืœื›ื ืžืฉื—ืจืจ ืืช ื”ื‘ืœื™ืค ื”ืžืชืœื•ื ืŸ ื”ืื—ืจื•ืŸ ืฉืœื•
00:12
and cuts out in the middle of your call.
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ื•ื—ื•ืชืš ื‘ืืžืฆืข ื”ืฉื™ื—ื”.
00:14
In that moment, you may feel more like throwing your battery across the room
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ื‘ืื•ืชื• ืจื’ืข, ืืชื ืื•ืœื™ ืžืจื’ื™ืฉื™ื ื™ื•ืชืจ ืจืฆื•ืŸ ืขื– ืœื”ืฉืœื™ืš ืืช ื”ืกื•ืœืœื” ืฉืœื›ื ืœืจื•ื—ื‘ ื”ื—ื“ืจ
00:18
than singing its praises,
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ืžืืฉืจ ืœื”ืœืœ ืื•ืชื”,
00:20
but batteries are a triumph of science.
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ืื‘ืœ ืกื•ืœืœื•ืช ื”ืŸ ื ื™ืฆื—ื•ืŸ ืฉืœ ื”ืžื“ืข.
00:24
They allow smartphones and other technologies to exist
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ื”ืŸ ืžืืคืฉืจื•ืช ืœืกืžืจื˜ืคื•ื ื™ื ื•ื˜ื›ื ื•ืœื•ื’ื™ื•ืช ืื—ืจื•ืช ืœื”ืชืงื™ื™ื
00:28
without anchoring us to an infernal tangle of power cables.
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ื‘ืœื™ ืœืขื’ืŸ ืื•ืชื ื• ืœืกื‘ืš ื›ื‘ืœื™ ื—ืฉืžืœ ื ื•ืจืื™.
00:32
Yet even the best batteries will diminish daily,
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ื•ืขื“ื™ืŸ ืืคื™ืœื• ื”ืกื•ืœืœื” ื”ื˜ื•ื‘ื” ื‘ื™ื•ืชืจ ืชื™ื’ืžืจ ื™ื•ื ื™ื•ืžื™ืช,
00:35
slowly losing capacity until they finally die.
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ืœืื˜ ืœืื˜ ืชืื‘ื“ ืืช ื™ื›ื•ืœืช ื”ืงื™ื‘ื•ืœ ืฉืœื” ืขื“ ืฉืœื‘ืกื•ืฃ ืชืžื•ืช.
00:39
So why does this happen,
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ืื– ืœืžื” ื–ื” ืงืŸืจื”,
00:41
and how do our batteries even store so much charge in the first place?
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ื•ืื™ืš ื”ืกื•ืœืœื•ืช ืฉืœื ื• ืืคื™ืœื• ืื•ื’ืจื•ืช ื›ืœ ื›ืš ื”ืจื‘ื” ืžื˜ืขืŸ ืžื”ืชื—ืœื”?
00:45
It all started in the 1780s with two Italian scientists,
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ื”ื›ืœ ื”ืชื—ื™ืœ ื‘ 1780 ืขื ืฉื ื™ ืžื“ืขื ื™ื ืื™ื˜ืœืงื™ื™ื,
00:50
Luigi Galvani and Alessandro Volta,
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ืœื•ืื™ื’'ื™ ื’ืœื•ื•ื ื™ ื•ืืœืกื ื“ืจื• ื•ื•ืœื˜ื”,
00:53
and a frog.
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ื•ืฆืคืจื“ืข.
00:55
Legend has it that as Galvani was studying a frog's leg,
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ื”ืื’ื“ื” ืžืกืคืจืช ืฉื›ืฉื’ืœื•ื•ื•ื ื™ ื—ืงืจ ืจื’ืœ ืฉืœ ืฆืคืจื“ืข,
00:58
he brushed a metal instrument up against one of its nerves,
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ื”ื•ื ื”ื‘ืจื™ืฉ ื›ืœื™ ืžืชื›ืชื™ ืขืœ ืื—ื“ ื”ืขืฆื‘ื™ื,
01:02
making the leg muscles jerk.
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ืžื” ืฉื’ืจื ืœืฉืจื™ืจ ื”ืจื’ืœ ืœื”ืชืขื•ื•ืช.
01:04
Galvani called this animal electricity,
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ื’ืœื•ื•ื ื™ ืงืจื ืœื—ื™ื” ื”ื–ื• ื—ืฉืžืœ,
01:07
believing that a type of electricity was stored in the very stuff of life.
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ืžืื—ืจ ื•ื”ืืžื™ืŸ ืฉืกื•ื’ ืฉืœ ื—ืฉืžืœ ื ืื’ืจ ื‘ื—ื•ืžืจ ื”ื—ื™ื™ื.
01:12
But Volta disagreed,
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ืื‘ืœ ื•ื•ืœื˜ื” ืœื ื”ืกื›ื™ื,
01:13
arguing that it was the metal itself that made the leg twitch.
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ื•ื˜ืขืŸ ืฉื–ื• ื”ื™ืชื” ื”ืžืชื›ืช ืขืฆืžื” ืฉื’ืžื” ืœืขื•ื•ื™ืช ื‘ืจื’ืœ.
01:17
The debate was eventually settled with Volta's groundbreaking experiment.
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ื”ื•ื•ื™ื›ื•ื— ื”ื•ื›ืจืข ืœื‘ืกื•ืฃ ืขื ื”ื ื™ืกื•ื™ ื”ืžื”ืคื›ื ื™ ืฉืœ ื•ื•ืœื˜ื”.
01:22
He tested his idea with a stack of alternating layers of zinc and copper,
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ื”ื•ื ื‘ื“ืง ืืช ื”ืจืขื™ื•ืŸ ืฉืœื• ืขื ืขืจืžื” ืฉืœ ืฉื›ื‘ื•ืช ืžืชื—ืœืคื•ืช ืฉืœ ืื‘ืฅ ื•ื ื—ื•ืฉืช,
01:27
separated by paper or cloth soaked in a salt water solution.
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ืฉื”ื•ืคืจื“ื• ืขืœ ื™ื“ื™ ื ื™ื™ืจ ืื• ื‘ื“ ื˜ื‘ื•ืœื™ื ื‘ืชืžื™ืกืช ืžื™ ืžืœื—.
01:32
What happened in Volta's cell is something chemists now call oxidation and reduction.
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ืžื” ืฉืงืจื” ื‘ืชื ืฉืœ ื•ื•ืœื˜ื” ื”ื•ื ืžืฉื”ื• ืฉื›ื™ืžืื™ื ืขื›ืฉื™ื• ืงื•ืจืื™ื ืœื• ื—ืžืฆื•ืŸ ื•ื—ื™ื–ื•ืจ.
01:38
The zinc oxidizes, which means it loses electrons,
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ื”ืื‘ืฅ ืžื—ืžืฆืŸ, ืžื” ืฉืื•ืžืจ ืฉื”ื•ื ืžืื‘ื“ ืืœืงื˜ืจื•ื ื™ื,
01:42
which are, in turn, gained by the ions in the water in a process called reduction,
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ืฉื ืืกืคื™ื ืขืœ ื™ื“ื™ ื”ื™ื•ื ื™ื ืฉืœ ื”ืžื™ื ื‘ืชื”ืœื™ืš ืฉื ืงืจื ื—ื™ื–ื•ืจ,
01:48
producing hydrogen gas.
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ื•ื›ืš ืžื™ื™ืฆืจื™ื ื’ื– ืžื™ืžืŸ.
01:50
Volta would have been shocked to learn that last bit.
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ื•ื•ืœื˜ื” ื”ื™ื” ื”ืžื•ื ืœื’ืœื•ืช ืืช ื”ื—ืœืง ื”ืื—ืจื•ืŸ ื”ื–ื”.
01:53
He thought the reaction was happening in the copper,
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ื”ื•ื ื—ืฉื‘ ืฉื”ืชื’ื•ื‘ื” ื”ืชืจื—ืฉื” ื‘ื ื—ื•ืฉืช,
01:56
rather than the solution.
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ื‘ืžืงื•ื ื‘ืชืžื™ืกื”.
01:58
None the less, we honor Volta's discovery today
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ืขื ื–ืืช, ืื ื—ื ื• ืžื›ื‘ื“ื™ื ืืช ื’ื™ืœื•ื™ื• ืฉืœ ื•ื•ืœื˜ื” ื”ื™ื•ื
02:01
by naming our standard unit of electric potential "the volt."
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ืขืœ ื™ื“ื™ ืžืชืŸ ืฉืžื” ืฉืœ ื”ื™ื—ื™ื“ื” ื”ืกื˜ื ื“ืจื˜ื™ืช ืฉืœ ืคื•ื˜ื ืฆื™ืืœ ื—ืฉืžืœื™ "ื”ื•ื•ืœื˜."
02:05
This oxidation-reduction cycle creates a flow of electrons between two substances
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ืžื—ื–ื•ืจ ื”ื—ื™ืžืฆื•ืŸ ื—ื™ื–ื•ืจ ื”ื–ื” ื™ื•ืฆืจ ื–ืจื ืฉืœ ืืœืงื˜ื•ืจื ื™ื ื‘ื™ืŸ ืฉื ื™ ื”ื—ื•ืžืจื™ื
02:11
and if you hook a lightbulb or vacuum cleaner up between the two,
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ื•ืื ื”ื™ื™ื ื• ืžื—ื‘ืจื™ื ื ื•ืจื” ืื• ืฉื•ืื‘ ืื‘ืง ื‘ื™ืŸ ืฉื ื™ื™ื
02:15
you'll give it power.
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ื”ื ื™ืงื‘ืœื• ื›ื•ื—.
02:17
Since the 1700s, scientists have improved on Volta's design.
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ืžืื– ื”ืžืื” ื” 18, ืžื“ืขื ื™ื ืฉื™ืคืจื• ืืช ื”ืขื™ืฆื•ื‘ ืฉืœ ื•ื•ืœื˜ื”.
02:21
They've replaced the chemical solution with dry cells filled with chemical paste,
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ื”ื ื”ื—ืœื™ืคื• ืืช ื”ืชืžื™ืกื” ื”ื›ื™ืžื™ืช ืขื ืชืื™ื ื™ื‘ืฉื™ื ืžืœืื™ื ืžืฉื—ื” ื›ื™ืžื™ืช,
02:26
but the principle is the same.
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ืื‘ืœ ื”ืขื™ืงืจื•ืŸ ื–ื”ื”.
02:28
A metal oxidizes, sending electrons to do some work
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ืžืชื›ืช ืžืชื—ืžืฆื ืช, ืฉื•ืœื—ืช ืืœืงื˜ืจื•ื ื™ื ืœืขืฉื•ืช ืขื‘ื•ื“ื”
02:32
before they are regained by a substance being reduced.
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ืœืคื ื™ ืฉื”ื ืžืชืงื‘ืœื™ื ืขืœ ื™ื“ื™ ื—ื•ืžืจ ืฉืžืชื—ื–ืจ.
02:35
But any battery has a finite supply of metal,
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ืื‘ืœ ืœื›ืœ ืกื•ืœืœื” ื™ืฉ ืžืœืื™ ืžื•ื’ื‘ืœ ืฉืœ ืžืชื›ืช,
02:38
and once most of it has oxidized, the battery dies.
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ื•ื‘ืจื’ืข ืฉืจื•ื‘ื• ื”ืชื—ืžืฆืŸ, ื”ืกื•ืœืœื” ืžืชื”.
02:42
So rechargeable batteries give us a temporary solution to this problem
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ืื– ืกื•ืœืœื•ืช ื ื˜ืขื ื•ืช ื ื•ืชื ื•ืช ืœื ื• ืคืชืจื•ืŸ ื–ืžื ื™ ืœื‘ืขื™ื” ื”ื–ื•
02:46
by making the oxidation-reduction process reversible.
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ืขืœ ื™ื“ื™ ื”ืคื™ื›ืช ืชื’ื•ื‘ืช ื”ื—ืžืฆื•ืŸ ื—ื™ื–ื•ืจ.
02:50
Electrons can flow back in the opposite direction
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ืืœืงื˜ืจื•ื ื™ื ื™ื›ื•ืœื™ื ืœื–ืจื•ื ื—ื–ืจื” ื‘ื›ื™ื•ื•ืŸ ื”ื”ืคื•ืš
02:53
with the application of electricity.
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ืขื ื”ื•ืกืคืช ื—ืฉืžืœ.
02:56
Plugging in a charger draws the electricity from a wall outlet
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ื—ื™ื‘ื•ืจ ืžื˜ืขืŸ ืžื•ืฉืš ื—ืฉืžืœ ืžื”ืฉืงืข ื‘ืงื™ืจ
02:59
that drives the reaction to regenerate the metal,
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ืฉืžื ื™ืข ืชื’ื•ื‘ื” ืœืฉื—ื–ืจ ืืช ื”ืžืชื›ืช,
03:02
making more electrons available for oxidation the next time you need them.
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ืžื” ืฉื’ื•ืจื ืœื–ื” ืฉื™ืฉ ื™ื•ืชืจ ืืœืงื˜ืจื•ื ื™ื ื–ืžื™ื ื™ื ืœื—ืžืฆื•ืŸ ื‘ืคืขื ื”ื‘ืื” ืฉื ื–ื“ืงืง ืœื”ื.
03:07
But even rechargeable batteries don't last forever.
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ืื‘ืœ ืืคื™ืœื• ืกื•ืœืœื•ืช ื ื˜ืขื ื•ืช ืœื ืžื—ื–ื™ืงื•ืช ืœืขื“.
03:10
Over time, the repetition of this process causes imperfections
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ื‘ืžืฉืš ื”ื–ืžืŸ, ื”ื—ื–ืจื” ืขืœ ื”ืชื”ืœื™ืš ื”ื–ื” ื’ื•ืจืžืช ืœืคื’ืžื™ื
03:14
and irregularities in the metal's surface that prevent it from oxidizing properly.
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ื•ื—ื•ืกืจ ืื—ื™ื“ื•ืช ืขืœ ืคื ื™ ื”ืžืชื›ืช ืฉืžื•ื ืขื™ื ืžืžื ื” ืœื”ืชื—ืžืฆืŸ ื‘ืื•ืคืŸ ื™ืขื™ืœ.
03:19
The electrons are no longer available to flow through a circuit
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ื”ืืœืงื˜ืจื•ื ื™ื ืœื ื–ืžื™ื ื™ื ื™ื•ืชืจ ืœื–ืจื•ื ื“ืจืš ื”ืžืขื’ืœ
03:22
and the battery dies.
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ื•ื”ืกื•ืœืœื” ืžืชื”.
03:24
Some everyday rechargeable batteries
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ื›ืžื” ืกื•ืœืœื•ืช ื ื˜ืขื ื•ืช ื™ื•ื ื™ื•ืžื™ื•ืช
03:27
will die after only hundreds of discharge-recharge cycles,
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ื™ืžื•ืชื• ืื—ืจื™ ื›ืžื” ืžืื•ืช ืžื—ื–ื•ืจื™ื ื‘ืœื‘ื“ ืฉืœ ืคืจื™ืงื” ื•ื˜ืขื™ื ื”,
03:31
while newer, advanced batteries can survive and function for thousands.
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ื‘ืขื•ื“ ืกื•ืœืœื•ืช ื—ื“ืฉื•ืช, ืžืชืงื“ืžื•ืช ื™ื•ืชืจ ื™ื›ื•ืœื•ืช ืœืฉืจื•ื“ ื•ืœืชืคืงื“ ืœืžืฉืš ืืœืคื™ื,
03:36
Batteries of the future may be light, thin sheets
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ืกื•ืœืœื•ืช ื‘ืขืชื™ื“ ืื•ืœื™ ื™ื”ื™ื• ื™ืจื™ืขื•ืช ื“ืงื•ืช ื•ืงืœื•ืช
03:39
that operate on the principles of quantum physics
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ืฉืคื•ืขืœื•ืช ืขืœ ื”ืขืงืจื•ื ื•ืช ืฉืœ ืคื™ื–ื™ืงื” ืงื•ื•ืื ื˜ื™ืช
03:42
and last for hundreds of thousands of charge cycles.
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ื•ื™ืฉืจื“ื• ืžืื•ืช ืืœืคื™ ืžื—ื–ื•ืจื™ ื˜ืขื™ื ื”.
03:45
But until scientists find a way to take advantage of motion
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ืื‘ืœ ืขื“ ืฉืžื“ืขื ื™ื ื™ืžืฆืื• ื“ืจืš ืœื ืฆืœ ืืช ื”ืชื ื•ืขื”
03:49
to recharge your cell battery, like cars do,
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ื›ื“ื™ ืœื˜ืขื•ืŸ ืืช ื”ืกื•ืœืœื” ืฉืœ ื”ืกื•ืœื•ืจื™ ืฉืœื›ื, ื›ืžื• ืฉืžื›ื•ื ื™ื•ืช ืขื•ืฉื•ืช,
03:51
or fit solar panels somewhere on your device,
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ืื• ืœื”ืจื›ื™ื‘ ืชืื™ื ืกื•ืœืจื™ื™ื ื”ื™ื›ืŸ ืฉื”ื•ื ืขืœ ื”ืžื›ืฉื™ืจ,
03:54
plugging your charger into the wall,
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ื—ื™ื‘ื•ืจ ื”ืžื›ืฉื™ืจ ืฉืœื›ื ืœืงื™ืจ,
03:56
rather than expending one battery to charge another
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ื‘ืžืงื•ื ืœืจื•ืงืŸ ืกื•ืœืœื” ืื—ืช ื›ื“ื™ ืœื˜ืขื•ืŸ ืืช ื”ืฉื ื™ื”
03:59
is your best bet to forestall that fatal "bleep."
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ื”ื™ื ื”ืคืชืจื•ืŸ ื”ื˜ื•ื‘ ื‘ื™ื•ืชืจ ืฉืœื›ื ืœื“ื—ื•ืช ืืช ื”ื‘ืœื™ืค ื”ืงื˜ืœื ื™ ื”ื–ื”.
ืขืœ ืืชืจ ื–ื”

ืืชืจ ื–ื” ื™ืฆื™ื’ ื‘ืคื ื™ื›ื ืกืจื˜ื•ื ื™ YouTube ื”ืžื•ืขื™ืœื™ื ืœืœื™ืžื•ื“ ืื ื’ืœื™ืช. ืชื•ื›ืœื• ืœืจืื•ืช ืฉื™ืขื•ืจื™ ืื ื’ืœื™ืช ื”ืžื•ืขื‘ืจื™ื ืขืœ ื™ื“ื™ ืžื•ืจื™ื ืžื”ืฉื•ืจื” ื”ืจืืฉื•ื ื” ืžืจื—ื‘ื™ ื”ืขื•ืœื. ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ื”ืžื•ืฆื’ื•ืช ื‘ื›ืœ ื“ืฃ ื•ื™ื“ืื• ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ ืžืฉื. ื”ื›ืชื•ื‘ื™ื•ืช ื’ื•ืœืœื•ืช ื‘ืกื ื›ืจื•ืŸ ืขื ื”ืคืขืœืช ื”ื•ื•ื™ื“ืื•. ืื ื™ืฉ ืœืš ื”ืขืจื•ืช ืื• ื‘ืงืฉื•ืช, ืื ื ืฆื•ืจ ืื™ืชื ื• ืงืฉืจ ื‘ืืžืฆืขื•ืช ื˜ื•ืคืก ื™ืฆื™ืจืช ืงืฉืจ ื–ื”.

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