????????????????????????????????
`
`SCIENCE MADE SIMPLE
`HOW DO BATTERIES WORK?
`
`Protons and electrons have what is called an
`“electric charge.” Protons have a “positive”
`charge. Electrons have a “negative” charge.
`Neutrons have no charge; they are neutral.
`Positive and negative are opposite charges.
`Things with opposite charges attract, or pull
`towards each other. Things that have the same
`kind of charge repel, or push apart from each
`other.
`
`+
`+
`
`-
`-
`
`OPPOSITE CHARGES ATTRACT
`
`+ -
`-+
`
`+
`
`+ -
`
`-
`
`LIKE CHARGES REPEL
`
`Batteries power things like flashlights,
`toys, radios and watches. There are
`many kinds of batteries in different
`shapes and sizes. Some seem to last
`longer than others before they wear out.
`Have you ever wondered:
`How do batteries work?
`
`What Is Energy?
`Batteries provide energy. What is energy?
`
`Energy is the ability to do work,
`or to make something happen.
`
`There are many different kinds of energy. These
`include heat, light, chemical and electrical
`energy. Energy can change from one kind to
`another.
`Batteries store chemical energy. When the
`ends of a battery are connected together, the
`chemical energy is changed to electrical energy.
`The electrical energy can be used to do work.
`
`ELECTRONS
`
`Everything Is Made Of Atoms
`Everything in the world around you is made
`of very tiny particles called atoms. And atoms
`are made of even smaller particles called
`protons, neutrons and
`electrons. The protons
`and neutrons
`are
`packed very tightly
`together in the center of
`the atom. This is called
`the nucleus. Whirling
`around the nucleus are
`smaller particles called
`electrons.
`
`NUCLEUS
`
`Electricity
`In atoms, negative electrons are attracted to
`positive protons. So atoms hold most of their
`electrons very tightly.
`But some electrons near the outside of an
`atom are not held as tightly. They may be able
`to move from one atom to another. Materials
`whose electrons move easily from atom to atom
`are called conductors. (Most metals are good
`conductors.)
`
`IN A CONDUCTOR, ELECTRONS
`MOVE EASILY FROM ATOM TO ATOM
`
`© Copyright 2004 by Science Made Simple, Inc.
`PO Box 503, Voorhees, NJ 08043
`www.sciencemadesimple.com
` science@sciencemadesimple.com
`
`page 1
`
`APPLE 1118
`Apple v. GUI
`IPR2021-00470
`
`

`

`SCIENCE MADE SIMPLE
`
` How Do Batteries Work?
`
`Usually the electrons in a conductor move
`in all different directions. Sometimes, they will
`all move in the same direction. This flow of
`electrons is called electricity, or electric current.
`
`Current is the flow of charged particles.
`
`There are two things needed for current to
`flow. The first is a path it can flow through. This
`continuous, unbroken path is called a circuit.
`The second thing is a force to push the
`electrons through the circuit. This force is called
`voltage.
`Voltage exists when there is a difference in
`the electric charge between two places. If there
`is a path, electrons will move from the place with
`a negative charge toward the place with a
`positive charge. Current flows because positive
`and negative charges attract each other.
`Voltage is measured in volts. A flashlight
`battery produces about 1.5 volts. The electric
`lines coming into houses in the U.S. carry about
`115 volts. Long-distance power lines can carry
`hundreds of thousands of volts.
`
`FUN FACTS
`HOW FAST DOES CURRENT FLOW?
`
`When you flip on a light switch, the light comes on
`instantly. That is because electric energy travels close
`to the speed of light. However, the charged particles
`themselves move much more slowly. The electrons may
`only travel a few centimeters per minute along the
`copper wire.
`
`How Does a Battery Work?
`Inside a battery are several kinds of
`chemicals. These chemicals store energy.
`Chemicals can react with each other and change
`into different chemicals. Some reactions give off
`extra electrons. Other reactions require electrons
`to take place. When the ends of a battery are
`connected together, there is a path for the
`movement of electrons. The chemicals react.
`The stored chemical energy is changed to
`electrical energy, and current flows.
`
`+ -
`
`+ -
`
`SWITCH IS OPEN.
`NO ELECTRICITY FLOWS.
`
`SWITCH IS CLOSED.
`ELECTRICITY FLOWS.
`THE BULB LIGHTS UP.
`
`BATTERY CROSS-SECTIONS
`
`ALKALINE BATTERY
`
`Positive terminal
`
`CARBON ZINC (FLASHLIGHT) BATTERY
`
`Positive terminal
`
`Outer jacket
`
`Steel case
`
`Cathode
`(manganese
`dioxide & carbon)
`
`Separator
`
`Seal &
`air space
`
`Cathode
`(carbon rod)
`(carbon &
`magnesium
`dioxide)
`
`Protective
`case
`
`Anode
`(zinc)
`
`Electrolyte
`paste
`
`Separator
`
`Negative terminal
`
`page 2
`
`Negative terminal
`
`Anode
`(zinc)
`
`Anode
`collector
`(metal rod)
`
`Seal &
`vent
`
`

`

`SCIENCE MADE SIMPLE
`
` How Do Batteries Work?
`
`HOW ALKALINE BATTERIES WORK
`
`--
`
`Zn
`
`Zn+2
`
`+
`
`When the battery terminals are connected together, zinc atoms
`in the anode give up two electrons. The zinc atoms become
`positively charged. The electrons flow out of the battery and
`through the circuit, doing work.
`
`- + MnOO
`
`-
`MnOO
`
`Electrons return to the battery through the cathode.
`Manganese dioxide molecules take up electrons and become
`negatively charged.
`
`MnOO- HOH
`+
`
`Zn+2
`
`+
`
`-OH
`
`+
`
`-OH
`
`+ HOH
`
`ZnO
`-OH+
`
`MnOOH
`
`Electrolyte is located in both the cathode and the anode. The
`charged manganese dioxide reacts with water in the
`electrolyte. The water breaks apart into H+ and OH-. The H+
`combines with the manganese dioxide. The OH- moves to
`the anode. There, it combines with the positively charged zinc,
`making zinc oxide and water.
`page 3
`
`There are three main parts to a battery: the
`electrolyte, and two electrodes. Working
`together, these parts make up a “cell.”
`The negative (-) electrode is called the anode.
`It is made of a material which gives up electrons
`easily. Usually, the anode is a metal.
`The positive (+) electrode is called the
`cathode. It is made of a material which can take
`in (or accept) the returning electrons. The
`cathode is often made of a metal oxide. (An oxide
`is a material that has reacted and combined with
`oxygen.)
`When the battery terminals are connected in
`a complete circuit, a chemical reaction takes
`place. The metal in the anode gives up electrons.
`The electrons flow out of the battery and through
`the circuit. This electric current can be used to
`do work, like light a bulb or turn a motor. Then
`electrons flow back into the other end of the
`battery. The cathode collects those electrons.
`To complete the circuit, the electrons have to
`flow from the cathode back to the anode. That
`is the job of the electrolyte. The electrolyte can
`be a liquid, paste or solid material. In some kinds
`of batteries, the electrolyte is located between
`the electrodes. In other kinds of batteries the
`electrolyte is mixed in with the electrodes.
`Without an electrolyte to carry the electrons, the
`battery would not work.
`
`Battery Sizes
`Batteries come in many shapes and sizes.
`Some of the most common are the 1.5 volt,
`cylinder-shaped “D”, “C” and “AA” batteries.
`Why are there different sizes? The bigger
`batteries contain larger amounts of chemicals
`and so can provide more energy than smaller
`batteries.
`
`Primary Batteries
`Many batteries use up one of their chemicals
`to make electricity. They are called primary
`batteries. When the chemical is gone, the battery
`stops working. It must be recycled or thrown
`away.
`A common kind of primary battery is the
`carbon-zinc battery. It is sometimes called a dry
`cell or flashlight battery. As a zinc-carbon cell
`
`

`

`SCIENCE MADE SIMPLE
`
` How Do Batteries Work?
`
`works, zinc is changed into zinc oxide. When
`the zinc is gone, the battery is dead.
`The carbon-zinc battery is often used in toys
`or flashlights. It is inexpensive, but it wears out
`quickly. The carbon-zinc battery used today is
`very similar to a cell invented in the 1860’s.
`There are now many newer, better kinds of
`batteries.
`One of these is the alkaline battery. Alkaline
`batteries last much longer than carbon-zinc
`batteries. They use different materials inside.
`The electrolyte is an alkaline chemical called
`potassium hydroxide. Instead of being in a
`separate layer, it is mixed in with both electrodes.
`These batteries produce more energy for a longer
`period of time.
`Anther common primary battery is the
`mercury cell. It is often used in things like
`watches and hearing aids because it can be made
`as a small flat disk.
`
`Secondary (Rechargeable) Batteries
`Secondary batteries are rechargeable. They
`make electricity by changing one of their
`chemicals into another form. When all of the
`chemical has been changed, the battery stops
`working. But it can be recharged. Sending
`
`current through the battery in the opposite
`direction changes the chemical back to its
`original form. Rechargeable batteries can be
`used over and over again.
`Lead-acid batteries are a common type of
`secondary battery. They can produce strong
`current for a short time. This is useful for starting
`an engine, and lead-acid batteries are used in
`automobiles, trucks and airplanes.
`Another common rechargeable is the alkaline
`nickel-cadmium cell, or Ni-Cad. It is light
`weight and often used for cordless appliances
`and other portable equipment. Ni-Cad batteries
`also:
`• produce very high current, which is good for
`starting and turning motors.
`• can be rapidly recharged many, many times.
`However, Ni-Cad batteries often show a
`“memory effect.” They produce less energy after
`repeated use. They work better and last longer
`if they are fully discharged and recharged each
`time.
`Many other kind of batteries are available for
`special uses. And research into new and
`improved batteries continues as scientists look
`for cheaper, smaller, more powerful and longer-
`life batteries.
`
`WORD PUZZLE
`Taking care of batteries
`
`1) _____ dispose of batteries
`in a fire because they could
`explode.
`
`N
`
`2) Remove batteries from
`equipment which will not
`be used for several _____
`to prevent them from leaking or corroding.
`
`M
`
`3) Do not use different kinds of
`batteries (alkaline & zinc),
`or mix new and _____ batteries
`together in the same equipment.
`
`4) Follow instructions carefully when inserting batteries.
`Make sure the + and - _____ are lined up correctly.
`
`R
`
`5) Do not try to ______ a regular battery, because it could
`explode.
`
`R
`
`D
`
`6) Answer the following question using the letters
`from the squares above: Who invented the battery?
`
`(Answers are on page 8)
`
`page 4
`
`

`

`SCIENCE MADE SIMPLE
`
` How Do Batteries Work?
`
`ELECTRONS
`
`I CAN READ
`HOW DO BATTERIES WORK?
`the chemicals give up electrons.
`Everything around
`The electrons flow out of the battery
`you is made of very
`and along the path, where they can
`tiny parts called
`do work. The electrons go back in
`atoms. Atoms are
`PROTONS
`the other end of the battery. Inside,
`much too small to
`& NEUTRONS
`different chemicals collect the
`see. And atoms are made of even
`returning electrons. So, as the
`smaller parts. These are called
`chemicals change, the battery
`protons, neutrons and electrons.
`makes electricity.
`Atoms hold onto most of their
`electrons very tightly. But some
`electrons can move
`from one atom to
`another.
`Sometimes the electrons all
`move in the same direction. This
`is called electricity, or electric
`current.
`
`+ -
`
`+ -
`
`SWITCH IS OPEN.
`NO ELECTRICITY FLOWS.
`
`SWITCH IS CLOSED.
`ELECTRICITY FLOWS.
` THE BULB LIGHTS UP.
`Some batteries use up their
`chemicals. Then they stop working.
`They must be recycled or thrown
`away.
`Electricity needs a path to move
`Other batteries are rechargeable.
`through. Then it can do work.
`They have different chemicals
`Electricity can light a light bulb or
`inside. The chemicals change as the
`turn a motor. It can run a watch
`battery works. When all the
`or a computer.
`chemicals have changed, the battery
`Batteries make electricity.
`stops working. You can recharge the
`How? Batteries have chemicals
`battery by putting electricity
`inside. These chemicals hold
`through it in the opposite direction.
`energy. When you connect the
`This changes the chemicals back.
`ends of a battery together, there is
`They are ready to be used again.
`a path electricity can flow
`Rechargeable batteries can be used
`through. The chemicals in the
`many times before they must be
`battery start to change. Some of
`thrown away.
`page 5
`
`

`

`SCIENCE MADE SIMPLE
`
` How Do Batteries Work?
`
`LEARN MORE ABOUT:
`ELECTRICAL CIRCUITS
`
`Series Circuits
`The parts of a circuit can be
`connected together different ways:
`in series or in parallel.
`In a series circuit, the parts are
`connected one after the other
`along a single path. The same
`amount of current flows through
`each part of the circuit.
`
`Parallel Circuits
`In a parallel circuit, the path
`splits into more than one branch.
`Different amounts of current may
`flow through each of those
`branches. More current will flow
`through the branches with lower
`resistance. Less current will flow
`through the paths with higher
`resistance.
`
`+ -
`
`SERIES CIRCUIT
`
`+ -
`
`PARALLEL CIRCUIT
`
`Connecting Batteries Together
`The power sources for a circuit can also be
`connected either in series or parallel.
`If you connect two batteries in series, then the
`battery voltages are added together. For example,
`two 1.5 volt batteries in series will produce 3.0 volts.
`If you connect two batteries in parallel, then the
`voltage remains the same. However, they can
`provide twice the amount of current or last longer
`than a single battery.
`In many applications, multiple batteries are
`connected in series to increase the voltage available.
`
`CONNECTING 1.5 VOLT BATTERIES
`+ 3 volts -
`
`+ - + -
`
`BATTERIES
`IN SERIES
`PROVIDE MORE
`VOLTAGE
`
`Electrical Circuits
`Some things run on one battery. Other equipment
`needs two or more batteries to work. These batteries
`may be lined up and connected in different ways.
`Why?
`Different kinds of equipment need different
`voltages and currents to work. This determines how
`many butteries it needs, and how the batteries are
`connected.
`Circuits can be simple, for example, a flashlight.
`Or they can be complex, like a computer chip. But
`each circuit has three main parts. There is an energy
`source, like a battery. There is a conductor through
`which the current flows. And there is a load, which
`is the equipment needing power.
`
`Measuring Electricity
`There are four important measurements that
`describe the flow of electricity. They are voltage,
`current, resistance and power.
`Voltage is the force that makes electric current
`flow. (It is also known as electromotive force, electric
`potential, or potential difference.) It is measured in
`volts. Common flashlight batteries produce a voltage
`of 1.5 volts. Car batteries provide 12 volts. Household
`current in the U.S. is normally about 115 volts. A
`single stroke of lightening discharges between 10
`million and 100 million volts.
`Current is the flow of charged particles. It is
`measured in amperes, or amps. A 100-watt light bulb
`carries about 1 amp. One amp is about 6 quintillion
`(a 6 followed by 18 zeros) electrons flowing past a
`point each second. A television set carries about 3
`amps, and a toaster about 10 amps. An average stroke
`of lightening carries about 30,000 amps.
`As electrons move through a conductor, they
`bump into the atoms. These collisions change the
`electrons’ speed and direction. The material itself
`interferes with, or resists, the flow of current. This is
`called resistance. Good conductors have low
`resistance. Materials which do not conduct current
`well are called insulators. They have very high
`resistance. Resistance is measured in ohms.
`Electric current carries energy. Energy is
`measured in units of joules or ergs. The rate at which
`energy flows is called power. Power is often
`measured in joules per second, or watts. The amount
`of power is calculated by multiplying voltage times
`current. The higher the voltage or current, the greater
`the power.
`
`BATTERIES
`IN PARALLEL
`PROVIDE MORE
`CURRENT
`
`+
`
`1.5 volts
`
`-
`
`+ -
`
`+ -
`
`page 6
`
`

`

`SCIENCE MADE SIMPLE
`
` How Do Batteries Work?
`
`about 2 volts. To make a 12-volt car battery, six cells
`are connected together in series. Inside a nine volt
`“transistor radio” battery are six 1.5 volt cells hooked
`together in series.
`
`+-
`
`+ -
`
`+-
`
`+ -
`
`? volts
`
`+-
`
`SOME EQUIPMENT USES BATTERIES
`INSTALLED IN ALTERNATING DIRECTIONS.
`WHAT VOLTAGE DO THESE FOUR 1.5 VOLT
`BATTERIES PROVIDE?
`
`(ANSWERS ARE ON PAGE 8.)
`
`It is rare to find equipment with batteries connected
`in parallel. When more current or longer life is
`needed, a larger battery is used instead. For example,
`“D” cells provide more energy than “C” cells, and
`“C” cells provide more than “AA” cells.
`Batteries themselves are often made of more than
`one cell. Combining cells produces higher voltage
`or more current. For example, lead-acid batteries are
`used in automobiles. Each lead-acid cell produces
`
`FUN FACT - WHY CAN’T YOU START A CAR
`WITH 8 FLASHLIGHT BATTERIES?
`
`Eight flashlight batteries in series would provide 12 volts, the
`same as a car battery. However, the flashlight batteries can not
`provide enough current to turn the car’s engine. The current a
`battery can produce is limited by its “internal resistance.” The
`lead-acid car battery has a lower internal resistance than the
`flashlight batteries, and it can produce a higher instantaneous
`current flow.
`
`PROJECTS TO DO TOGETHER
`
`SAFETY NOTE: Read all instructions completely before starting. Observe all safety precautions.
`
`PROJECT 1 - Make a Salt Water Battery
`
`What you need:
`a small, battery-powered LCD clock or calculator (project works best if it uses a single 1.5 volt battery)
`or a small LED (which can be purchased at any electronics store, for example, Radio Shack)
`insulated copper wire, wire strippers
`aluminum foil, salt, water, small glasses or cups, tape, scissors
`What you do:
`(1) Cut 3 pieces of wire, about 30 - 45 cm (about 12 - 18 inches) long. Carefully strip about 3 cm (about 1
`inch) of insulation from both ends of each wire.
`(2) Cut two pieces of aluminum foil, each about 5 cm (about 2 inches) square. Wrap a foil square foil tightly
`around one end of two of the wires. Make sure the copper is completely covered. Press it tightly to make
`sure there is good contact between the wire and the foil. Tape the foil to the wire’s insulation.
`(3) Remove the battery from the clock. Attach the wire without foil to the positive clock terminal. Attach the
`copper end of one of the foil wires to the negative clock terminal. It is important to attach the wires to the
`correct terminals. Make sure there is GOOD CONTACT between the wires and the terminals, then tape
`them down. (Getting good electrical contacts is the most difficult part of this experiment. You can test the
`contacts by holding the battery against the loose ends of the attached wires, to see that the clock works.)
`(4) Fill two small glasses with about 250 ml (about 1 cup) of warm water. Add
`about 15 cc (about 1 tablespoon) of salt to each and stir until it dissolves.
`(5) Place the clock near the glasses. Put the loose ends of the wires attached to the
`clock into the salt water in the glasses. Tape them down.
`(6) Put the copper end of the third wire into the glass with the foil wire. Put the
`foil end of the third wire into the glass with the copper wire. Each glass should
`have the ends of two wires, one foil and one copper, as shown. Make sure that
`the ends of the wires do not touch each other. Tape down the third wire.
`
`12:00
`-
`+
`
`page 7
`
`

`

`SCIENCE MADE SIMPLE
`
` How Do Batteries Work?
`
`(7) The clock should display the time. If not, check that the wires make good contact with the clock terminals
`and the aluminum foil. If it still does not work your clock may need more voltage. Try adding more “cells”
`in series to generate higher voltage.
`What Happened: The “battery” in this experiment is a set of salt-water/copper/aluminum cells connected
`together in series. When the circuit is complete, the salt water reacts with the copper wire and aluminum
`foil. The reactions produce electric current, powering the clock. Each cell produces about 0.5 to 0.6 volts,
`and the two cells connected in series produce about 1 to 1.2 volts. Using different metal electrodes would
`make cells that generate different amounts of voltage.
`
`PROJECT 2 - Make a Lemon Battery
`
`What you need:
`a small, battery-powered LCD clock or calculator, or a small LED
`a lemon, cut in half
`insulated copper wire, wire strippers
`aluminum foil, a dish, tape, scissors
`
`12:00
`-
`+
`
`What you do:
`(1) Repeat steps (1) through (3) of Project 1. You may reuse the same wires,
`clock, etc.
`(2) Put the lemon halves on a dish, not touching each other. Place the clock near the dish. Put each of the
`loose ends of the wires attached to the clock into one of the lemon halves.
`(3) Take the third wire and put each end into one of the lemon halves. Each lemon half should have the ends
`of two wires, one foil and one copper, as shown. Make sure that the ends of the wires are close together but
`do not touch each other.
`(4) The clock should display the time. If not, check that the wires make good contact with the clock terminals
`and the aluminum foil. If it still does not work, your clock may need more voltage. Try adding more “cells”
`in series to generate higher voltage.
`What Happened: The “battery” in this experiment is a set of lemon/copper/aluminum cells connected
`together in series. When the circuit is complete, chemicals in the lemon react with the copper wire and
`aluminum foil. The reactions produce electric current, powering the clock. Each cell produces about 0.5
`volts, and the two cells connected in series produce about 1.0 volt. Using different metal electrodes would
`make cells that generate different amounts of voltage.
`A similar experiment is often found in books. That project uses a single lemon attached to a regular
`flashlight bulb. It will not work because a lemon battery does not generate enough current to light a
`regular bulb.
`
`ANSWERS TO PUZZLE ON PAGE 5
`
`1) NEVER (2) MONTHS (3) OLD (4) TERMINALS (5) RECHARGE
`
`(6) VOLTA - The Italian scientist Alessandro Volta (1745-1827) made the first battery around 1800. He
`used a stack of alternating silver and zinc disks, separated by paper soaked in salt water. When the top
`silver disk was connected to the bottom zinc disk, the chemical reaction produced current.
`
`ANSWER TO QUESTION ON PAGE 7
`
`This arrangement would produce 6 volts.
`
`page 8
`
`