Magnets we are most familiar with are just magnetize steel bars bent into the familiar U
shape. Magnetic fields are are invisible. Nobody knows what they made of let a lone what it is.
Every bar magnet suspended in a sling will align across the north/south
direction. One end is attracted by the earth's north pole and the other end repelled by the south pole
like a cumpas. The magnet is pulled and pushed round at the same time.
We can identify the North and
South seeking poles sticking an N for the North seeking and S for the
south seeking pole each each end. We can color code with green for the North seeking pole and
red for the south seeking pole.
If we press together the north seeking poles of any two magnets we feel a repelling force. So
too if we press the south seeking ends together. Powerful magnets can feel as if
a solid without even touching the ends. The same is true when we bring together
two North
seeking poles together. As soon as we let go the
unlike poles poles crash the magnets together. You
will feel an equal force prizing the unlike poles apart. This is known as the like repel and unlike attract law.
The unit of all magnetic fields is Weber. 1Wb is a magnet powerful enough to attract a
kilogram steel block a meter away in a second. The magnets we encounter on a daily basis
the standard metric prefix system prefix mill (mill-lee) for 1 divided by a thousand. As a rule of thumb we can tell the strength by the repelling and
attractive forces. Toy magnets are pretty week about a few millimeters. Strong commercial
magnets as much as 250 a
quarter Weber. 500 is half and and 750mWb three quarters of a Weber.
Iron filings trace the fields. Place any magnet under paper. Sprinkle the fillings over
the paper. They will
clump each end tracing the shape of the magnetic field though the paper. There are lots of magnet shapes, donuts to magnetized steel balls. The Iron fillings
will trace the magnetic field round any shape.
The north and south seeking magnetic fields interact with an electric current. Any touch battery
will tell you is made of positive and negative forces stored in each terminal.
Every battery terminal is marked with a plus sign (+) for the
positive end and a takeaway minus sign ( - sometimes unmarked) for the negative
terminal. (+ - ).
It is known as an electromotive Force known by the unit voltage. It is a live positive and negative
electromotivec force. They don't flow. They are only alive at each terminal. Proof of this
when you press together the ends of two touch cells (Batteries if you like) about a millimeter
gap and gently move from side to side. You should
feel a week magnetic field force just like you felt with the magnets.
Just like a magnet you are feeling the like repel and unlike law in action. The plus to plus
(+ +) and minus to minus (- - ) ends repel each other. The plus and minus ends
(+ -) attract each other. If
you rub the terminals with the tip of a needle you will start to experience hints
of iron fluff sticking to it. It is most pronounced when
you using a magnet. Strong magnetism can
magnetized screw driver tips. The magnetize tip will be less than a milliWeber about a 100 Microweber
(Micro for 1 divide a million) about a 10th of a milliweber and only last a few minutes.
An electric current
only flows when there is a load connected in parallel with (across) the two
terminals. The current flow is made up of the orbiting particle of the atom called electrons
stored in the negative terminal. The moving flow unit is amperage. 1 amp is a trillion
electrons close to the speed of light. Expensive rechargeable torch batteries are
capable of producing more than an amp under full voltage under a dead short. Cheep specially well used batteries will have
potential voltage
drop called Potential difference (pd) at a minimal current supply.
The negative terminal is an access electrons making it somewhat domineeringly
negative. The positive terminal lacks
the same number making it somewhat domineeringly positive. When a load is connected in parallel with the two voltages the negatively charged
electrons are repelled by the negatively
charged terminal attracted by the positively charged terminal direction.
The positive terminal drains
electrons from the negative terminal filling in the missing electron spaces in
the positive terminal like nails fly to a magnet. When the terminals balance the battery is known to be
flat. This is known as the electron current flow direction. Depending on the
resistance to the electron current is pushed by the nearest negative and pulled to the
positive voltage
direction in a steady direct current stream know as Direct Current. This is known as the electronm current flow.
The resistance of all loads are in parallel with the two voltages drawing the
electron current known as the current drain. The
combined voltage and current the power output known by the unit Wattage. Cheep new torch batteries are only capable of
a maximum of a volt with a maximum of a few milliamps current supply. These
small ones are typically 1.5V with a total voltage drop of half volt. Better quality
will supply the maximum voltage and current for an extended period time.
Expensive single torch batteries (1.5V torch cells) are capable of a maximum voltage with a high
current supply of a few amps more than a minute under a dead short. This is
known as an amp hour ratting. 1 Amp hour torch battery will last an hour with a
current drain of 1Amp before the voltage starts to wane. Typical long lasting
high quality torch batteries supply 500mA, (half amp) meaning they last an hour with a
current drain of 500mA before loosing voltage. Heavy loads means a low
resistance in parallel with the source meaning a high current drain and high voltage drops.
Dead shorts are under an Ohm resistance supplying the maximum current supply. The total current drain of any load is
the resistance of the load in parallel with any voltage. The higher the resistance the less current supply
and the higher the voltage. The lower the resistance the higher the current drain
and the
more the voltage drops. High current drains aer potential voltage drop
problems.
To much voltage is sign of too low current drain a
sign of a too low current limiting resistance that should not be somewhere in
the circuit. A high voltage that should not be is when a load is drawing to low current
a sign of a high current limiting resistance that should not be
somewhere in the circuit.
Batteries last longer with low current drain and shorter with high current drains.
The current drain of any load determines the lasting power of any battery source.
The power of any circuit starts with the current drain it draws from the
source. The circuit's current drain should be specified as the amp hour ratting
of the source or the amp hour ratting chosen by the current drain of the circuit
required. An audio project aimed at full volume at the loudest part of the audio
as the total current drain drawn from the audio circuit draws for example.
The combined total voltage and current drain is the total power drain of the
load on the source. A high power drain (High wattage) potentially drops voltage. Expensive
torch cells are capable of supplying high power drain from a load with out effecting the total voltage for a short period of time.
Watts W equals E I law tells us the he total Wattage supply is the total voltage
across the load multiplied the maximum current drain.
The power of any DC power supply arrangement depends on the cost of the the
battery pack arrangement. Cheep new batteries only supply as little as a
maximum of 10mA with a substantial voltage drop because of a high
internal resistance. A single expensive of the largest torch
cell and
Latten batteries have a maximum voltage and current supply supplying high wattage
under the load of low resistance. The internal resistance of expensive cells is less than an ohm even under
a dead short.
Expensive high wattage torch batteries are ideal for demonstrating
electric current create electric magnets. Cheep well used cells are not ideal as
they are low Wattage. High Wattage battery output is required because using of low
current limiting resistances the toorch cell can handle. Cheep cells are useless batteries that have high internal current limiting resistance at maximum voltage drops under
heavily loads.
High wattage batteries are ideal.
1.5V with a current suply of 1.5A equals 1.5W in an hour before loosing voltage.
They have a lot of current supply at the maximum current due to low internal
resistance under the load of a low resistance load. One amp hour torch battery and a piece ofctronic
hobby hook up wire is all you need. Use a long piece cut to about a half meter (about 50cm)
should be enough.
You will need to strip away a tip of the outer insulation ends exposing just
enough of the inner conducting wire for taping in electrical contact to the terminals.
Seleotape the exposed inner
conducting wire ends. When connected the freshly charged large high amp hour
torch battery will show evidence the straight piece of wire is magnetized.
Cheep lower power batteries
haven't the power under this kind of dead short. Proof of the high power of a
1wh battery when the wire
collects iron fillings it tends pick up. As you play round with experiments
you will notice the wire getting very fluffy with picking up loose iron fillings
close by.
Disconnect the battery till you have wound round a pencil dozens turns leaving a length at each end to connect to
the battery. A touch of clued helps prevents frustrating unraveling and and convenient
for sliding off the pencil.
1.5Ah torch batteries are capable of producing
the maximum voltage and it's maximum current supply. Depending on the current drain
of the coil winding the electron current flows
though the winding spinning round and round each turn as it goes. Each turn is magnetized. You will be able to pick up tacks with
just one 1.5V, 1.5Ah torch battery.
Each turn of the winding adds a resistance thus lowering
current drian drain on power supply. Coil windings will draw a minimal
current in a moment accelerating to maximum accelerating down to a constant
current drain
expressed as a time constant. Time constant to reach constant current drain can
last less than a second to a few seconds. The coil winding is a current limiting
inductor.
The unit of inductors is Henrys. In radio engineering the current limiting
resistance time const is often used in circuit design. A high Hennery inductors are high resistance
and a low Hennery is a low resistance inductor. The specified inductance of
an inductor depends on the power drain on the source that determines the current drain
to handle the low inductance. A single 1.5Ah torch
battery is ideal. The growth in current is the time the coil winding reaches
maximum voltage and current drain.
The power of single 1.5Ah torch batteries will have enough voltage and current
supply to produce a North and south magnetic poles at the ends of the coil
winding. Cheep run down sizes nothing. They have not enough power. The electric magnet and the magnet will attract
and repel each other. The electric magnet will be attracted to
the earth's magnetic poles just like a magnet.
You will find the electric magnet and
the magnet will attract and repel each other. Note you will be constantly be cleaning annoying fluff off the parts the magnet and electric magnet they
constantly collect.
When you disconnect you have removed the power source where the magnetic field
has no where to collapse to. Large torch batteries have the power
to demonstrate sparking across the gap. Cheep well used are never ideal. The
coil winding is a dead short with theses batteries. They produce a minimum voltage
and current supply for the spark.
Removing the coil winding from the pencil replacing it with a steel rod the
power of the electric current will magnetize the metal tube. You have an
electric magnet complete with the North and South seeking poles at each end of the
rod acting just like a magnet.
Disconnecting the battery if you rapidly move in and out a bar magnet inside any coil winding the poles
of each end magnetizes each turn. There will be an alternating North and South
seeking magnetic pole passing across each turn in the coil. There will be a rise
and fall of one polarity and a rise and fall of the other.
Connecting a touch
bulb in parallel with (across) the winding as one pole passes across the winding
the bulb lights brightly and dimly the
frequency you moved in and out the magnetic poles. This is because of a corresponding plus and
minus electrical voltage exists across the winding.
The electron current flow is set up repelled by the rise and fall of the
negative voltage in one direction.
Then they are attracted by the corresponding
rise and fall of the positive voltage the rising and falling the opposite
direction. Both the winding and bulb is alive alternating positiev and negative
voltage and back and forth though electron current from the moving in and out
bar magnet inside the coil winding.
Both the bulb and winding will throb from minimum brightness to minimum the frequency of the rapidly passing magnetic fields.
This is the basics of alternating current. The unit of the frequency is Hertz.
One cycle per second. The faster the magnet oscillates in and out of the coil winding the higher the frequency
of the winding and bulb oscillates.
In machines bar magnets are either pressed into a drum circling fixed coil
windings or a fixed coil winding spinning inside a fixed magnetic field the
basics of a bicycle dynamo. This depends on the design of the designers choice
of method. The drive can be a water wheel driven by the fall of water falling on
the vanes turning the magnetic field or coil windings the basic principle of
power stations producing the ac mains power.
To produce DC what are called slip rings divert electron current
direction going the same direction the basis of bicycle
dynamos. An electronic component known as a semiconductor called a diode is a
high current limiting resistance one direction. When you turn the diode round
has a low resistance.
Connected in series with a bulb are in parallel with the two ac voltages.
There will be a positive and negative voltage across the both ends of each
component that equal to the total voltage across them. Knowing the total current
drain of the two components together the total resistance can be projected by
what is known as Ohms law. The total voltage across them dived divided by the
total current drain will give the total resistance of the load, I equals E over
I law respectively.
If the bulb and diode are in parallel they will split up the total
alternating current drain between them with the same ac voltage across both components.
Electronic components in parallel are low resistance thus high current drains on
the rapidly moving in and out poles of the magnet. In series low resistance thus
low current drains. The total resistance of the components.
The electronic symbol of a diode is a straight line with arrow head in the
center. This arrow head always points in the low resistance direction of the electron current
flow. The arrow head direction is always the low resistance direction. Opposing
the arrow (back of the arrow head) is always the high resistance direction. Thus
the diode conducts a high current drain the direction of the arrow head and a
low current back of the arrow head. There will be an alternating high and low
electron current.
The direction of the electron current flow tells us there is always a
negative voltage at the arrow end and a positive voltage at the back of the
arrow head giving the DC voltage output polarities no matter way the diode is
arranged. The arrow head always points to the negative voltage direction. The
back always the positive. In wiring diagrams a plus sign at the back of the
arrow head and a minus sign at the arrow point. If the dilled is reversed the
polarities are reverse.
If a component called a capacitor is connected in parallel with the output
across the bulb the back and forth electron the oscillating from the back and
forth magnetic poles the corresponding back and forth electron current charges
the capacitor one way and the bulb in parallel with the capacitor discharges it
back into the circuit the back and forth frequency of the rapidly moved in and
out magnet poles of the magnet.
The added current drain will take current away
from the other tow components the peaks of the bulb will glow less as the
capacitor shears the total current drain with them. The result is a smooth DC
output though the less bright bulb.
The design of the output from the coil winding is in the current drain
specifications though the bulb governed by milliweber and frequency of the in
and out magnet required from magnetic poles and the number of turns in the
winding to compensate for the total loading of the components.
The output power
design should start the strength and frequency of the poles can handle the load
of the coil winding. Toy magnets are pretty well under powered. Strong magnets
are the best choice.
