how the ranges of the permanent magnet type voltmeter and ammeter can be extended??
823030
You could use a resistor in series for the voltmeter and a shunt resistor in parallel with the ammeter.  You can also use a signal amplifier to transform the input signal to one that is within the range of the meter.  If it is a panel type meter, do not forget to change the scale behind the meter.\n\nJeffM
734023
It sounds like you need a multi-meter which is handy for all your electric household needs. You can measure current with most of these and they can be found in hardware stores like Ace in most cases and possible even at places like Wal-Mart. They are not uncommon items. If you want you might be able to go online and search for a amp meter most likely from a physics teacher website. I'm sure your nearest hardware store will carry coil but if not, Radioshack is an option. Problem with Radioshack that I have had is too much money for too little quantity (this is in general and not specific to the coils) if you have time, you can browse the internet for teacher selling sites but you may have to pay for shipping which might also run up the cost. The magnets really depend on what scale you are talking about. Hobby Stores will definitely carry small craft magnets but if you need really strong magnets your best bet is once again a teacher website. I hope that I have been at least some use to you, and best of luck on your experiment/project.
25444
You could try to make an accurate experimental thermometer by glueing two strips of dissimilar metals together along their lengths. Perhaps try copper and steel or copper and aluminum or steel and aluminum.  Try perhaps one half inch wide by six inch long strips.  Use sheets of metal that are equally thin.  Perhaps cut the strips from aluminum soda cans and steel soup cans, etc.  Use a magnet to check for steel vs aluminum.  Glue the strips together using epoxy or super glue.  Attach one end of the combined strip to a firm base and leave one end free to move in front of a paper scale.  You now have a bimetalic thermometer.  The thermometer can be made to be more sensitive by using greater length strips and bending the strips into a spiral and attaching a pointer to the free end of the spiral to amplify movement.  This is how most oven thermometers are built except the metals are joined without glue.  The principal of operation of a bimetalic thermometer is that one  metal expands or contracts more or less than another metal.  When joined, a temperature change causes the combined strip to bend.  You can calibrate your thermometer by marking its "pointer" position at two or more large temperature changes then calculating the total deflection divided by the total temperature difference to get deflection per degree (either F or C).  Be careful with tin snips and epoxy or super glue.  Good luck.\n\nAs an alternative, you can make a highly accurate experimental thermometer by winding very thin insulated copper wire (like that used in toy motors) around a wooden spool and connecting the scraped   wire ends to an accurate ohmmeter to measure resistance change vs temperature change.  Calibrate as before but remember that calibration temperatures must be steady long enough for any lag to catch up.  This is called a resitance thermometer and accuracy will depend on the length and thinness of wire and sensitivity of your ohmmeter.  Also the ohmmeter should not cause enough current to flow in the wire to heat the wire.  Observe for drift (increase in resistance and temperature) while taking measurements.
610327
electromagnetic or magnetic fields. It is easiest to research and to do the practical of. Just place the magnets and use iron filings to measure it
1161474
You can't. The polarity of a magnet is set. If you screw it up, sorry!
323504
You can buy them in chip form. I think Analog Devices makes them, up to eight bit. They are easier to use and more accurate than anything ou could build from discrete parts.
997515
vernier callipers \nmeasuring weights\nmagnet bars\nIC tester\nvoltmeter\nammmeter\nenergy meter\nMultimeter\nDC Power Supply \nFunction Generator \nDigital Multimeter \nOscilloscope \npower wires\nBreadboard\nresitors \ncapacitors\nvoltage divider and current divider circuits
119991
It is an instrument for measuring the strength of a magnetic field and has various applications, including locating mineral deposits, archaeological sites, submerged objects, or in my primary application, measuring the past magnetic field orientation of the earth as recorded in rock samples in order to establish an age of deposition. \n\nWhat you buy or build depends on your application. The magnetometer I have used is the size of a small car. I have seen towable marine-type magnetometors for sale on eBay for under $2000, and I have seen others listed on the internet for under $500. The difference is likely to be the sensitivity. There are also instructions on the web for building your own. Here's a build your own:\nhttp://www.portup.com/~dfount/proton.htm\nHe has added  a good list of resources and references.
655524
http://en.wikipedia.org/wiki/Magnetic_Flux_Leakage\nThis is real good
455603
If it's for a simple hobbyist application they need to know only the resistance value and its power rating.\n\nA full specification would also include:\n\ntolerance,  thermal coefficient,  maximum voltage.
444083
If you move the magnet through the core of the solenoid, the fluxing magnetic field will induce an electric current in the wires which can be measured using the amp meter.
403112
use swinging field dynamo meter/ reaction principle.
1173860
http://www.oz.net/~coilgun/theory/solenoidphysics.htm
166825
a hoffman voltmeter can easily be improvised if thats the apparatus you mean? no idiot questions please
1139339
The best way is to get it from the manufacturer.  If you don't know who made it, you can look up resistances from a bunch of places on the net if you know the wire gauge, but remember that copper resistance increases as it gets hot.  \n\nMost magnet wire can handle a few hundred volts with no troubles, but if you're doing some high voltage app, better be sure about the voltage rating.
364018
Ultrasonics appears to be a possible way. You can also check on www  GlobalSpec.com  , lots of stuff there.\nI forgot ! Eddy-current testing has been used for many years in non-destructive testing of non-ferrous metals.A probe with an alternating current of a frequency decided by the skin-depth of penetration can be used to measure impedance change near a crack etc. Alternately a dc current could be applied via a probe and possibly use a Hall plate sensor to detect field distortions. The subject is very interesting and there is much relevant work to be done.\nNow in the case of non-metallic materials, we can consider a capacitance measuring device; there must have been work done on this method.
261277
It's simple do this job. First of all you need to set your volt meter to a specific voltage level. Like if you want to check voltage of batteries, it ranges between 1.5 to 14 volts. So set your volt meter dail to DC (Direct Current) with this voltage specification.\nFor checking voltage in your house, its a 110-120 V or 220-240 V. This depends on your location. So now you have to set the dail to AC (Alternating current. THe symbol of AC is " ~ ".\n\nI', also a site here. It would solve the job definitly.\n\n\nhttp://www.ehow.com/how_16767_voltmeter.html