What is Ammeter: Definition and 89 Discussions

An ammeter (from ampere meter) is a measuring instrument used to measure the current in a circuit. Electric currents are measured in amperes (A), hence the name. The ammeter is usually connected in series with the circuit in which the current is to be measured. An ammeter usually has low resistance so that it does not cause a significant voltage drop in the circuit being measured.
Instruments used to measure smaller currents, in the milliampere or microampere range, are designated as milliammeters or microammeters. Early ammeters were laboratory instruments that relied on the Earth's magnetic field for operation. By the late 19th century, improved instruments were designed which could be mounted in any position and allowed accurate measurements in electric power systems. It is generally represented by letter 'A' in a circuit.

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  1. Femme_physics

    Ammeter in a problem, calculating currents

    Homework Statement http://img827.imageshack.us/img827/2602/thecircuit002.jpg This circuit is made out of 3 resistors and an ampmeter A whose internal resistance is Ra = 10 ohms 1) Calculate the flow going through the ampmeter where R1 = 20 ohms, R2 = 30 ohms, R3 = 50 ohms 2) Come...
  2. D

    How to Calculate Shunt Resistance for Converting a Galvanometer to an Ammeter?

    A galvanometer has a full scale current of 0.100 mA and a coil resistance of 50ohmes. In constructing an ammeter of 60mA full scale, what shunt resistnace is needed?I'm lost on this one.
  3. D

    Ammeter and Wattmeter in ac RLC circuit

    What type of power rating does a wattmeter measure in an AC RLC circuit? Is the power measured the apparent power or active power, and is this reading the rms value? Also which current value is taken by an ammeter in an AC rlc circuit? is this also rms value?
  4. B

    Test an Ammeter: 24V DC 100A Loads

    How can i test an ammeter with ratings 24V (dc) 100 A with any load? This is just to check whether the ammeter works in the defined range. What kind of source should i connect to get a current of maybe 25 or 50 amps.
  5. Z

    Conversion of a Galvanometer to an Ammeter

    I had this doubt for over 1 year! I thought of asking about it here. In the conversion of a galvanometer to an ammeter by connecting a shunt in parallel to the galvanometer, maximum amount of current flows through the shunt because it has a very very low resistance. In other words, very less...
  6. A

    How does a ammeter and voltmeter works?advanced thanks.

    how does a ammeter and voltmeter works? advanced thanks.
  7. C

    Does Aryton shunt=multirange ammeter?

    Homework Statement Aryton shunt=multirange ammeter? Homework Equations How to do this question? Design an Aryton shunt to provide an ammeter with a current range of 0-1mA,10mA,50mA and 100mA. A D'Arsoval movement with an internal resistance of 100ohm and full scale current of 50x10-6A...
  8. A

    Resistance of ammeter and voltmeter

    Homework Statement http://img638.imageshack.us/img638/2421/screenshot20100807at012.png Homework Equations The Attempt at a Solution For the ammeter resistance i chose to find the difference in the voltmeter reading in the two circuits. that difference is the p.d. across the...
  9. S

    Quick question on connecting ammeter, voltmeter

    first if i were to connect an ammeter i would connect it in a series correct? if i connect the ammeter in parallel what would happen? second if i were to connect a voltmeter i would connect it in parallel? if i connect the voltmeter in series what would happen?
  10. P

    High frequency from AC tig welder affects digital ammeter?

    I need a solution to the question, Which clamp-around-the-cable ammeter (digital or analog) can be trusted in measurement of current draw by a high-frequency AC tig welder? High-frequency AC is a requirement of welding aluminum, and an electrician measured 150+ amps at full power welding...
  11. M

    Designing an AC Ammeter with 0.15V Voltage and Currents of 200mA, 500mA, 1A

    Hello all! I must design an ac ammeter which uses successive approximation ADC,has a specified voltage of 0,15V and individual entrance resistors for measuring currents of 200mA,500mA,1A. Any suggestions on how to build such a device would be highly appreciated!
  12. L

    Understanding the Internal Resistance of Ammeters and Voltmeters

    Homework Statement I'm writing my sources of error for my lab report and I'm just wondering if its true that the ammeter has internal resistance in it, and that this will increase the resistance in the circuit, which will ultimately decrease the current in the circuit?? Does this sound right...
  13. N

    Designing an AC Ammeter: How to Find the Appropriate Resistance?

    Homework Statement I was assigned to design an ac ammeter.But i have no idea how to work on it and don't know how to find the R for the ac ammeter? Thx for the help! =] Homework Equations The Attempt at a Solution
  14. A

    Computer acquisition of analog ammeter reading

    Hi, My friends and I are doing a project that involves some very high (multiples of 10 kV and above) voltage, but very low current. The controller for our transformer has an analog ammeter on it, but we would like to have a computer read and recored the current readings from it. We have a...
  15. P

    Multirange Ammeter magnitudes homework

    Can someone please help me out with this problem? I am not sure if what I am doing The question: The resistance of the moving coil of the galvanometer G in Fig. 26.73 is 48.0 ohms, and the galvanometer deflects full scale with a current of 0.0200 A. When the meter is connected to the...
  16. M

    Measuring Capacitance given a voltmeter + ammeter

    Homework Statement Given the following: • a battery, • a digital voltmeter (which records voltage as a function of time), • a digital ammeter (which records current as a function of time), • a battered industrial capacitor, • two copper plates, • and several bits of copper wire...
  17. C

    Design an Ammeter - Know How to Measure Current

    Hihi, I put a photodiode's legs to both the input for a differential amplifier http://en.wikipedia.org/wiki/File:Op-Amp_Differential_Amplifier.svg Then, the voltage difference of the photodiode is amplified and its output is then connected to a resistor which is not shown in the above...
  18. L

    What is the reading shown by the ammeter?

    Homework Statement 3)An ammeter has a full scale deflection of 0.5 A.Internal resistance is 12 ohms.Explain with necessary calculations,how it should be converted to an ammeter of full scale deflection 2A. 4) does this modification change the sensitivity of the instrument?explain 5. The...
  19. T

    Ammeter and voltmeter resistance

    Homework Statement A little help with this one please The power in a 10ohm resister when connected to a 100v supply is measured by an ammeter and voltmeter. There are two possible ways of connecting the instruments (as seen in the attachment) The values of Ra and Rv represent the...
  20. R

    How can you use an ammeter to measure a voltage of 5.0 V?

    Homework Statement A circuit you're building needs a voltmeter that goes from 0 to a full-scale reading of 5.0 V. Unfortunately, the only meter in the storeroom is an ammeter that goes from 0 to a full-scale reading of 500 microA. It is possible to use this meter to measure voltages by...
  21. G

    Parallel resistors and ammeter problem

    Homework Statement A student mistakenly connects a perfect ammeter (i.e one of negligible resistance), in parellel with one of the two of the two identical resistors. The ammeter reads of 0.40 A. What would the reading have been if he had correctly connected the ammeter in series with two...
  22. J

    Internal resistance of an ammeter

    Homework Statement Devise a NON DESTRUCTIVE scheme to measure the resistance of the 0-1mA meter that is provided in the lab. You may make use of an external power supply (or battery) and other circuit components such as resistors to make your measurement. Design your measurement scheme so that...
  23. T

    A Multirange Coil Ammeter Galvonmeter (?) resistance question

    [SOLVED] A Multirange Coil Ammeter Galvonmeter (?) resistance question Homework Statement A Multirange Ammeter. The resistance of the moving coil of the galvanometer G in the figure (See Below) is 48 Ohms, and the galvanometer deflects full scale with a current of 0.0200 A. When the meter...
  24. S

    Circuit with ammeter , what does the voltmeter and battery read

    For the circuit both meters are idealized, the battery has no appreciable internal resistance, and the ammeter reads 1.25 . What does the voltmeter read? What is the emf of the battery? I tried this: 15 ohm and 10 ohm resistors are in series, hence equivalent to 25 ohm. Three...
  25. H

    Holy current, how do you find the the current at each ammeter?

    Holy current, how do you find the the current at each ammeter?? Homework Statement Find the current at each ammeter. My solution Someone told me to use \sumE-\sumIR=0 to solve the system but they weren't sure. But I cannot find anything about this on the internet and I'm freaking out!
  26. A

    Why do we convert a galvanometer into voltmeter and ammeter?

    why we convert a galvanometer into voltmeter and ammeter?
  27. H

    Ammeter Connections for Battery Current Measurement

    Homework Statement In which diagram(s) (labeled A - D) does the ammeter correctly measure the current through the battery? The Attempt at a Solution I know that ammeters measure the current in series, and that the voltmeter won't have any effect on its reading, but I'm confused about the...
  28. J

    Is there a low-cost programmable DC ammeter with serial port connectivity?

    Hello All, I've began to look all over the net to see if there are any programmable DC ammeters out there. For some of my projects, I want to have something like a current-flow data logger that I can read values directly from using the serial port. I have thought about making my own, but...
  29. K

    How much current (in A) flows through the ammeter for Circuit b?

    The manufacturer of a 12V car headlight specifies it will draw a current of 6A. You would like to check this claim with an ammeter designed to measure currents up to 10A and having a resistance of 0.1 Ohms. Which of the two figures below represents a circuit where the ammeter correctly measures...
  30. F

    Combined resistance of a cell and an ammeter

    [SOLVED] Combined resistance of a cell and an ammeter Homework Statement I had to do a lab where a 105cm 28 swg wire was used to find the combined resistance of a cell and an ammeter. The only apparatus was a switch, 1.5v cell, 0-1A ammeter, 105cm & 20cm wires and connecting wires. Switch...
  31. L

    Ammeter to help the circuit work

    Ammeter to help the circuit work! I have connected one IC circuit which is taking from a remote control car. Then I connect it to the a power supply which is 9V. It doesn't work in the beginning. But I don't know why it works after I connect an ammeter in parallel to the resistor which in in...
  32. S

    How to properly use an ammeter to monitor an electrolytic cell

    Hi i recently acquired an ammeter with a shunt can anyone explain how to wire this so i can measure amps in an electrolytic cell. Does the positive lead have to be wired across the shunt so that it doesn't burn out the lcd display. I've never used such an ammeter so any suggestions will be...
  33. H

    NEVER connect an ammeter in parallel ->WHY?

    "NEVER connect an ammeter in parallel!" -->WHY?! Why must an ammeter never be connected in parallel, or across the terminals of a power source? All I know about this is that you'll blow a fuse if you connect an ammeter in parallel... but I don't know why you'd blow a fuse. My guess: The...
  34. V

    How is the construction of an ac ammeter different from an dc ammeter

    Homework Statement How is the construction of an ac ammeter different from that of a dc ammeter? Homework Equations The Attempt at a Solution
  35. M

    Why Is a Voltmeter Connected in Parallel?

    hello i know why an ammeter is always in series with the resistor(s) but i don't know why a voltmeter is in parallel with the resistor(s) can somebody explain this? thank you:D
  36. O

    Multirange Ammeter and magnitudes of the resistances

    Can someone please help me out with this problem? I am not sure if what I am doing is right The question: The resistance of the moving coil of the galvanometer G in Fig. 26.63 is 43.0 ohms, and the galvanometer deflects full scale with a current of 0.0295 A. When the meter is connected to the...
  37. ranger

    Ammeter and voltmeter in circuit

    Why is that when I introduce an ammeter or a voltmeter into a circuit, it alters it. In other words how does a *meter affect the circuit? I read somewhere that when you measure the resistance [using an ammeter], it is slightly different from the actual value. Why does this happen? And one more...
  38. M

    Series Circuit Disconnected at Ammeter: Charge Flow?

    Hey i have a little question to ask... when a series circuit is broken (disconnected) at the negative terminal of the ammeter , does the charge flow around the circuit until it gets to the end of the line at the ammeter and then stop ? or does it stop at the moment when it's broken?
  39. S

    Why Does an Ammeter Have Higher Internal Resistance at Lower Current Ranges?

    We recently discovered that the internal resistance of an ammeter when using the 30 mA range is significantly larger than the internal resistance when using its 150 mA range. Despite the fact that I know this is correct, it seems counterintuitive. I would think that since an ammeter on the 30...
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