0
For capacitance measurement using a bridge is it more appropriate to use DC or AC Any diff in values?
Wiki User
∙ 15y ago
It is better to use AC. Impedance of the capacitor depends upon the frequency of the input signal. If we apply DC input signal than f = 0, that means Z approaches to infinity. If you apply the DC input signal then the current shall flow only for the time the capacitor is not charged. As the capacitor is charged current flow stops. At this point it is almost impossible to measure the voltage across capacitors because as you apply voltmeter across the capacitors, capacitors start to discharge through voltmeter (at this stage input impedance of the voltmeter is less as compared to that of capacitor).
So if you use AC then this situation does not occur, moreover you can control the impedance of the capacitor by varying the frequency of the input signal.
Regards
Muhammad Bilal Saif
If you have any further questions you can contact me at bilal_saif@giki.edu.pk
Wiki User
∙ 15y ago
Add your answer:
Earn +20 pts
How do you calculate cable distance using farads?
All underground cables have relatively high values of capacitance, due to the close proximity of their cores and earthed (grounded) metallic sheath. Manufacturers provide data for their cables, which express their capacitance in terms of capacitance per unit length, e.g. microfarads per metre.Certain categories of underground cable-fault can be located by measuring the capacitance (using an appropriate bridge circuit) of the healthy section of the cable then, having determined the capacitance per unit length for that type of cable, measuring-off the distance along the cable route to the fault position.
How does the Kelvin bridge differ from the wheatstone bridge?
kelvin's bridge is the modified version of wheatstone bridge and used to measure resistance values less than 1 ohm.
How are motor start capacitors rated?
Motor start capacitors are rated with two main values. One is capacitance in micro farads and the other is in voltage.
What do you measure capacitors in?
Capacitors are characterized by two values: their voltage, exceeding which will damage the capacitor (sometimes leading to a violent explosion), and their capacitance, as the name suggests. The voltage is expressed in volts. The capacitance is expressed in Farads. One (1) Farad is an amount of charge that makes the voltage across the capacitor terminals to rise by 1 Volt. If a 10mA current flows into the capacitor and it causes the capacitor's voltage to rise by 1V every second, the capacitor's capacitance is 10 milifarads. 1 Farad is a lot of charge, so for most applications, submultiples (microfarads and milifarads, mostly) are commonly used. A curious note: the more voltage a capacitor can handle, the (usually) bigger the size of it. At low voltages and low capacitance, the capacitance doesn't influence the size that much, though.
What device is used to change the scale values of an AC ammeter?
A multimeter is used in which there is options for multirange measurement of Ac current or voltages and resistances and also DC voltages
What refueling method is used when the capacitance values exceed corresponding maximum capacitance values?
discharged the capacitor
Which refueling method is used when the capacitance values exceed corresponding maximum capacitance values?
Quantity Select
How could you make a wien bridge tune to different frequencies?
Change one or more of the values of the inductance or capacitance of one or more of its legs.
What is a De Sauty's bridge and give explanation about it?
De Sauty's bridge is an electric component that provides a method for making a comparison between two capacitors. It measures the values in terms of a standard capacitance.
How do you calculate cable distance using farads?
All underground cables have relatively high values of capacitance, due to the close proximity of their cores and earthed (grounded) metallic sheath. Manufacturers provide data for their cables, which express their capacitance in terms of capacitance per unit length, e.g. microfarads per metre.Certain categories of underground cable-fault can be located by measuring the capacitance (using an appropriate bridge circuit) of the healthy section of the cable then, having determined the capacitance per unit length for that type of cable, measuring-off the distance along the cable route to the fault position.
Effects of stray capacitance in ac fan out?
due to the load gates capacitance values,there is a increased load capacitance on the driving gate
Using schering bridge how you find capacitance?
A Schering Bridge is a bridge circuit used for measuring an unknown electrical capacitance and its dissipation factor. The dissipation factor of a capacitor is the the ratio of its resistance to its capacitive reactance. The Schering Bridge is basically a four-arm alternating-current (AC) bridge circuit whose measurement depends on balancing the loads on its arms. Figure 1 below shows a diagram of the Schering Bridge.In the Schering Bridge above, the resistance values of resistors R1 and R2 are known, while the resistance value of resistor R3 is unknown. The capacitance values of C1 and C2 are also known, while the capacitance of C3 is the value being measured. To measure R3 and C3, the values of C2 and R2 are fixed, while the values of R1 and C1 are adjusted until the current through the ammeter between points A and B becomes zero. This happens when the voltages at points A and B are equal, in which case the bridge is said to be 'balanced'.When the bridge is balanced, Z1/C2 = R2/Z3, where Z1 is the impedance of R1 in parallel with C1 and Z3 is the impedance of R3 in series with C3. In an AC circuit that has a capacitor, the capacitor contributes a capacitive reactance to the impedance. The capacitive reactance of a capacitor C is 1/2πfC.As such, Z1 = R1/[2πfC1((1/2πfC1) + R1)] = R1/(1 + 2πfC1R1) while Z3 = 1/2πfC3 + R3. Thus, when the bridge is balanced:2πfC2R1/(1+2πfC1R1) = R2/(1/2πfC3 + R3); or2πfC2(1/2πfC3 + R3) = (R2/R1)(1+2πfC1R1); orC2/C3 + 2πfC2R3 = R2/R1 + 2πfC1R2.When the bridge is balanced, the negative and positive reactive components are equal and cancel out, so2πfC2R3 = 2πfC1R2 orR3 = C1R2 / C2Similarly, when the bridge is balanced, the purely resistive components are equal, soC2/C3 = R2/R1 orC3 = R1C2 / R2.Note that the balancing of a Schering Bridge is independent of frequency.
What are the likely maximum and minimum values for this measurement 20.4 0.1cm?
What are the likely maximum and minimum values for this measurement 20.4+_0.1cm
Why no negative values are chosen as values to substitute in for x?
They are, when appropriate.
Values that indicated the precision of a measurement?
Significant figures indicate the precision of a measurement.
What measurement uses absolute values?
distance
When the frequency in Hertz and the reactance positive or negative in Ohms are known can you determine component values such as inductance or capacitance?
Positive
