## WCLN – Cells and Batteries – Chemistry

Aug 17, 2014

The video explains the difference between a chemical cell and a battery. It shows how cells can be arranged to form a battery of cells in series or a battery of cells in parallel. It also shows how the total voltage supplied by a battery of cells in series or parallel can be calculated, given the voltage of an individual cell.

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0:00we’ll look at the difference between a
0:03cell and a battery when most of us see a
0:06device like this we call it a battery
0:09technically it’s not really called a
0:12battery it’s called a chemical sell the
0:16battery is actually defined as a
0:18combination of two or more chemical
0:20cells connected to each other for
0:23example if we attach the positive end of
0:25one cell to the negative end of another
0:27cell like this it forms a battery of two
0:32cells in series adding another cell like
0:35this
0:37will give us a battery of three cells in
0:40series
0:41the voltage of a cell is a measure of
0:43how much potential energy electrons gain
0:46as they go through a cell
0:49many common cells have a voltage of 1.5
0:52volt
0:54when cells are connected in series or
0:56positive to negative each sell ads
0:59potential energy to the electrons going
1:02through it
1:04so they’re voltages add up if a single
1:07cell has a voltage of 1.5 bolts
1:10two cells in series will have a total
1:13voltage of three volts
1:15to understand how this works we imagine
1:18one electron going through one cell
1:24as it goes through it picks up 1.5 volts
1:27of potential energy and goes into the
1:29other cell
1:31we’re the same electron picks up another
1:331.5 volts of potential energy
1:37so this single electron has picked up
1:391.5 volt potential energy from both of
1:43the cells
1:45so it is picked up a total of 1.5 plus
1:471.5 which is three bolts of potential
1:51energy
1:53therefore the voltage on the voltmeter
1:54is 3 volts
1:583 1.5 volt cells in series will have a
2:01total voltage a 1.5 plus 1.5 plus 1.5 or
2:09three times 1.5 which is equal to 4.5
2:12bolt
2:16look at a different arrangement when two
2:19cells are brought together
2:21so that their positive ends in line and
2:24there- and the line
2:27and the two positive and are connected
2:29by a conductor
2:31and the two negative ends are connected
2:33by a conductor
2:35they form a battery of two cells in
2:38parallel
2:40in parallel voltages do not add up
2:44for example if the voltage of oneself is
2:471.5 bolts
2:49and we add another cell and parallel
2:52the voltage will still be 1.5 volt
2:58even adding a third cell in parallel
3:00will still give us a voltage of 1.5
3:03volts
3:05to understand why this happens we
3:07consider two cells in parallel and two
3:10electrons by the voltmeter one of the
3:13electrons goes through oneself
3:16and picks up one point viable to
3:18potential energy
3:20and the other electron goes through the
3:23other cell
3:24and picks up 1.5 volts of potential
3:27energy
3:29so each electron has picked up potential
3:32energy from only one of the cells
3:35neither of the electrons go through both
3:38of the cells
3:41voltage is a measure of potential energy
3:43per electron
3:45each electron is picked up only 1.5
3:49volts
3:50so the voltage is still 1.5 volt
3:54to review a single unit like this is
3:57called the chemical cell rather than a
4:00battery
4:01when cells are connected with positive
4:03to negative a form of battery of cells
4:06in series
4:07when cells are connected in series their
4:12so for example the total voltage of 3
4:141.5 volt cells in series is equal to 1.5
4:18plus 1.5 plus 1.5
4:21which is 4.5 bolts when cells are
4:25arranged so they’re positive terminals
4:28are connected to a conductor and all
4:30their negative terminals are connected
4:32to another conductor a form a battery of
4:35cells in parallel and when cells of
4:39equal voltage are arranged in parallel
4:42the total voltage of the battery is
4:45saying as a voltage of a single cell

WCLN – Cells and Batteries – Chemistry
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