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a meter uses its own supply to measure resistance. you dont have to remove the resistor from the circuit but you must isolate it from the circuit supply to get an accurate reading.

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When checking resistance does the power have to be off?

Short answer: yes. Most modern multimeters will not be damaged by external power when measuring resistance. But they will give erroneous readings. It is best to remove the power and disconnect the measured resistance from the larger circuit. A multimeter determines resistance by applying a small voltage, and measuring the resulting current. If the resistor has an external voltage source, then it will interfere with the measurement. Furthermore, if the resistance is connected to a larger circuit, then the resistance of this larger circuit will also be involved.


Why it is advisable to remove the source and complete the circuit by internal resistance or by a link instead of short circuiting the terminals of the supply?

Because many electronics, like power supplies, have internal energy storage in the form of capacitors. If you were to short the terminals, you would be shorting out the internal capacitors and thus creating a potentially hazardous situation. "Completing the circuit by internal resistance" allows the energy stored in the internal capacitors to bleed off slowly because the internal resistance is larger than a short.


What voltage would you expect to measure across closed switch?

Original Correct Answer:The voltage across an open switch should equal the supply voltage.More Detailed Answer:The above answer is basically correct. However, it may not be EXACTLY the supply voltage.This is counter-intuitive at first glance and confuses a lot of people, including electrical engineers. The reason is this. Voltage, Current and Resistance are all interrelated by Ohms Law. Voltage equals Current multiplied by Resistance.It is easy to think that since a switch is open, then you do not have current flow through the circuit. Thus, current times any Resistance is equal to zero volts because the current is equal to zero. Thus, by this logic, you would expect to find zero volts across the switch. In actuality this is true.But, when you insert you meter, you change the conditions of the circuit, and the following is the result.Let's say that you have a circuit with a resistance load like a heater, and a inductive load like a motor. The switch that powers these devices is open, thus their is no current flowing through the resistance or inductive loads.Now you put the meter across the open switch. When you do, you insert a very large resistance in parallel to the open switch. Why? Because to get volts, the meter measures current flow through a known resistance, and then calculates voltage. To keep the resistance from impacting the circuit performance, the resistance is very large. Therefore, when you insert the meter, you will get a flow of current through the meter.Because of this large resistance, the current trough the resistance load, inductive load, and wires is very small. Thus, the voltage drop across the loads and wiring is very small. Therefore, it appears that the entire voltage in the circuit is across the huge resistance in the meter. The result is a voltage reading that is very near the source voltage.Let's do the math. Let's assume you have 120 volts. You also have a resistance of 500 ohms, and a motor winding that has 0 ohms resistance when DC is applied (This is true for motors). The meter has a 10 million ohm resistance.If these loads are in series, the total resistance is 10Million 500 ohms. The 11.9 microamps. By multiplying the current flow to each resistance, you get 6 millivolts across the resistance, no voltage across the motor winding, and 119.994 across the open switch or meter. Since a meter rounds it reading, you would get 120.If the loads are in parellel, you would get the same thing, becuase the switch is in series with both loads. In this example, the motor winding would have all the current flow through it since it is zero ohms, and the parallel resitance load is 500 ohms. Thus, the total resistance is the 10 million of the meter, and this resistance drive the current, and thus the largest voltage drop is at the swtich/meter. You could decide to remove the motor from this parellel circuit. If you did then the then the result is the series circuit above.


Susan remove the motor in circuit which increase the current how it affects bulb?

lol


What is exactly the function of Neutral link in an electrical circuit?

To protect a circuit, we use a fuse or circuit breaker. The fuse or circuit breaker must always be placed in the lineconductor, never in the neutral conductor. So, if we want to completely isolate a circuit from the supply, we must remove the fuse from the line conductor, and open the link in the neutral conductor. A 'link' is a non-fusible metal break point in the neutral.

Related Questions

How do you change the blower motor resistor in a 2001 Chevy prism?

Remove the glove compartment. Its behind it just to the left of the Blower. Disconnect the connector with four wires on the bottom. Remove two hex head screws, also from the bottom. I used a 7/32 socket to remove them. Remove resister. The resister looks like a small circuit board with printed circuit traces on it. Install new resister in reverse order.


When the resistor removed from a parallel connection of the circuit whether the resistance increase or decrease?

if we remove a resistor from the parallel connection the effective resistance value will be increased.


How do you calculate thevenis resistance in thevenis ckt?

First,remove all current and voltage sources ie replace voltage source with a short and keep current source open.Now draw the equivalent resistance-only circuit and find the equivalent resistance as viewed from the terminals of the circuit.


When checking resistance does the power have to be off?

Short answer: yes. Most modern multimeters will not be damaged by external power when measuring resistance. But they will give erroneous readings. It is best to remove the power and disconnect the measured resistance from the larger circuit. A multimeter determines resistance by applying a small voltage, and measuring the resulting current. If the resistor has an external voltage source, then it will interfere with the measurement. Furthermore, if the resistance is connected to a larger circuit, then the resistance of this larger circuit will also be involved.


How do you change the blower resistor on 99 CHEVY S-10?

Open hood, locate resister on passenger side of firewall, unplug the electrical connection, remove the three screws and remove resister.


What is common to both thevenin and norton theorem?

To solve any D.C. circuit by using Thevenin Theorem,First of all load resistance RL is disconnected from the circuit and open circuit voltage across the circuit is calculated (known as Thevenin equivalent voltage)Secondly, the battery is removed by leaving behind its internal resistance. Now we calculate equivqlent resistance of the circuit ( called Thevenin equivalent resistance).Now we connect Thevenin Voltage in series with Equivalent resistance of the circuit and now connect load resistance across this circuit to calculate current flowing through the load resistance.Whereas in the case of using Norton theorem, we again remove the load resistance if any, and then short circuit these open terminals and calculate short circuit current Isc.Second step is same as in Thevenin theorem i.e. remove all sources of emf by replacing their internal resistances and calculate equivqalent resistance of the circuit.Lastly, join short circuit current source in parallel with equivalent resistance of the circuit. Now, we can calculate votage across the resistance which was connected in parallel with Isc.So, by knowing the open circuit voltage, we can calculate current flowing the resistance and on the other hand , by knowing the short curcuit current , we can calculate voltage across the resistance.


Where is the blower resistor located on this vehicle?

There is an upper footwell panel on the front passenger side of the car. Remove the trim panel. This exposes the blower motor assembly. Find the electrical plug on the unit and unplug it. This will expose the resister screw and by removing the screw, you will be able to remove the resister for the blower. If the resister does not show continuity when tested with an ohm meter the resister needs to be replaced. If the resister shows continuity the problem may be the blower motor relay. Hope this helps on your 1998 Mystique.


How do you remove a defroster resister in a 02 Chevy s-10 rear wheel drive pickup truck?

Not sure what a defroster resister is, need more info please.


Where is the blower motor resister located on a 1996 Chevrolet 2500?

The blower motor resister block is located in the center of the dash. Remove the complete glovebox and look to the left and you will see it...............


How do you change a blower resister on a 2000 Chrysler Sebring JXI?

Behind the glovebox there is one panel to remove, then use a small socket to remove the two screws holding in the fan resister card and connector. You will need to lay on your back to do this using a light source.


How do you replace the rear blower motor resistor on a 2002 Chevy Trailblazer?

Remove the HVAC rear module auxiliary assembly.Disconnect the electrical connectors from the rear blower resister auxiliary.Remove the air outlet duct from the rear blower motor controller auxiliary.Remove the screws from the blower motor rear resister auxiliary.Remove the rear blower motor resister auxiliary.Replace the resister and install new thermal gasket.................


How do you use a multimeter to measure a short?

1.) Turn all the power in the circuit off. 2.) In volts mode (both AC and DC) check to make sure there is no power. 3.) In ohms mode check to see if the resistance is close to zero. (Check zero by connecting the leads together momentarily.) Note that light bulbs will have far less resistance cold than when hot, due to their negative temperature coefficient, so you should remove them, and that transformers and motors will appear to have zero ohms due to their inductive reactance, so they will also need to be pulled from the circuit.