0
How do you measure the resistance of a resistor with an ammeter and a voltmeter?
Wiki User
∙ 7y ago
If all you have is a voltmeter, then resistance can only be calculated. If you know the total volts applied and current, either total current if in series ckt or current through the component if parallel type ckt, then the following formulas apply: R=Eapp÷It (series ckt) R=Eapp÷IR (parallel ckt)
Wiki User
∙ 16y ago
Wiki User
∙ 9y agoOhm's Law, where I = V/R
I stands for Current in Amps, V stands for Voltage in Volts, and R stands for Resistance in Ohms.
Though, you an change up that equation and say that R = V/I
Answer
Unfortunately, you cannot use the method described in the original answer to accurately measure the resistance of a circuit because most circuits don't obey Ohm's Law!
To obey Ohm's Law, the ratio of voltage to current must remain constant for variations in voltage, and very few circuits behave like that. As the applied voltage increases, the ratio usually increases so that, at lower voltages, the resistance reading will be lower than at higher voltages.
For example, the resistance of a tungsten lamp can increase by up to 18 times from a low value of applied voltage up to its rated voltage. So, using the technique described will only tell you what the resistance happens to be at the voltage you use to perform the test.
A far-more accurate method for measuring resistance is to use a Wheatsone's Bridge circuit, the theory of which is beyond the scope of this forum. This compares the resistance of the circuit with other, known resistances, using a system of ratios.
Wiki User
∙ 11y agoThe ammeter will not change, it will still show the current. Placing a resistor in series only makes it less good as it will show more resistance. Placing a resistor parallel will change the current range.
The voltmeter will show a lower voltage as you have built a resistive voltage divider. Notice that nowadays voltmeters have very high input resistances, so you will need high ohmic resistors.
Wiki User
∙ 13y agoApply this, R = V/I, where V is the potential difference( in volt) and I is the current(in ampere)
Wiki User
∙ 13y agoResistance is connected in parallel with voltmeter or say, voltmeter is connected in parallel with resistance.
Add your answer:
Earn +20 pts
How does an ammeter work?
An ammeter is a low voltage voltmeter in parallel with a small resistance resistor. Current flow through the resistor creates a voltage drop across it which is then measured by the voltmeter.
How is an ammeter converted to a voltmeter?
The ammeter is used in series, because you want to measure the current through a circuit. The voltmeter is used in parallel, because you want to measure the voltage across a circuit. If you were to place the voltmeter in series, no current would flow because of the relatively high impedance of the voltmeter. If you were to place the ammeter in parallel, you would create a short-circuit, due to the relatively low impedance of the ammeter.
What device is used to measure the resistance of a resistor?
You can use a multi-meter to measure resistance. The specific portion of the meter for measuring resistance is called an ohmmeter.
Which will normally have the larger resistance a voltmeter or an ammeter?
A voltmeter has the large resistance.The voltage across any component can be measured if & only if the terminals of that component will be open and this will we can acheiv if we connect the high resistance voltmeter across the open terminals of that component to measure the voltage.
What is instrument specially designed to measure voltage?
The Ammeter XD
How does an ammeter work?
An ammeter is a low voltage voltmeter in parallel with a small resistance resistor. Current flow through the resistor creates a voltage drop across it which is then measured by the voltmeter.
How do you measure the resistance of a motor?
we can measure the resistance of the motor by using voltmeter ammeter method of by directly using a multimeter across the armature terminals of the motor in voltmeter ammeter method we should use a less value of dc voltage to find the resistance
Resistance and power measurement by voltmeter-ammeter method?
single phase power measure by three ammeter method
What is the Disadvantage of using an ammeter and voltmeter to measure resistance?
There will be errors. The error comes from the measured resistance size of the decision.
How is an ammeter converted to a voltmeter?
The ammeter is used in series, because you want to measure the current through a circuit. The voltmeter is used in parallel, because you want to measure the voltage across a circuit. If you were to place the voltmeter in series, no current would flow because of the relatively high impedance of the voltmeter. If you were to place the ammeter in parallel, you would create a short-circuit, due to the relatively low impedance of the ammeter.
How Determine the power dissipated by the resistor?
Power dissipated by the resistor = I^2 * R or V^2 / R, where R = its resistance value, I = the current in the resistor, and V = the voltage drop across the two terminals of the resistor. You need to measure or find the information of either I (using an ammeter) or V (a voltmeter).
What device is used to measure the resistance of a resistor?
You can use a multi-meter to measure resistance. The specific portion of the meter for measuring resistance is called an ohmmeter.
Which will normally have the larger resistance a voltmeter or an ammeter?
A voltmeter has the large resistance.The voltage across any component can be measured if & only if the terminals of that component will be open and this will we can acheiv if we connect the high resistance voltmeter across the open terminals of that component to measure the voltage.
What happens if an ammeter is connected in parallel and voltmeter connected in series in a circuit?
The voltmeter will register the volts, the ammeter will either explode or blow a fuse since it has a very low resistance and is designed to be used in series to measure the current flowing through it.
What is instrument specially designed to measure voltage?
The Ammeter XD
How you convert ammeter into voltmeter?
An ammeter measures the voltage across a resistor with a known value, andfrom that it calculates the current through the resistor. The resistor has to bea very small value, so that it doesn't change the current in the circuit by beingplaced in line with it.If you really want to do this, then you need a resistor made for the purpose,with a resistance of not more than 1 ohm. You can buy one, or maybe roll upa big ball of insulated wire that has a resistance of 1/2 or 3/4 ohm. (How youwould measure that accurately is another question.) When you have thatfractional-ohm resistor, connect the voltmeter across its ends, and you haveyour ammeter. To use it, open (break) the circuit whose current you want tomeasure, and connect your meter into the hole. Read the voltmeter. Thecurrent passing through your resistor is(the voltmeter reading) divided by (the resistance of your resistor).There are other design details to consider, which we won't go into at this time.If you actually try this, don't use it to measure currents greater than maybe1 Ampere. How will you know the current before you've measured it ? That'sexactly the appropriate question. The answer is: Experience. If you haven'tgot it, then maybe you shouldn't be building your own test equipment yet.
How do you convert voltmeter into ammeter?
An ammeter measures the voltage across a resistor with a known value, andfrom that it calculates the current through the resistor. The resistor has to bea very small value, so that it doesn't change the current in the circuit by beingplaced in line with it.If you really want to do this, then you need a resistor made for the purpose,with a resistance of not more than 1 ohm. You can buy one, or maybe roll upa big ball of insulated wire that has a resistance of 1/2 or 3/4 ohm. (How youwould measure that accurately is another question.) When you have thatfractional-ohm resistor, connect the voltmeter across its ends, and you haveyour ammeter. To use it, open (break) the circuit whose current you want tomeasure, and connect your meter into the hole. Read the voltmeter. Thecurrent passing through your resistor is(the voltmeter reading) divided by (the resistance of your resistor).There are other design details to consider, which we won't go into at this time.If you actually try this, don't use it to measure currents greater than maybe1 Ampere. How will you know the current before you've measured it ? That'sexactly the appropriate question. The answer is: Experience. If you haven'tgot it, then maybe you shouldn't be building your own test equipment yet.
