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You can reduce the size of the plates (thus making the capacitor smaller physically) if you also do one or both of the following:
- move the plates closer together (which also reduces size, but lowers the breakdown voltage)
- use a dielectric with a higher dielectric constant
Of course these changes must be made at the time of manufacture, they cannot be done to change an existing capacitor.
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A circuit contains a 10 pF capacitor and a 50 pF capacitor connected in parallel.What is the total capacitance of this circuit?
When capacitors are connected in parallel, the total capacitance in the circuit in which they are connected is the sum of both capacitances. Capacitors in parallel add like resistors in series, while capacitors in series add like resistors in parallel.
What is the effect of dielectric on the capacitance of a capacitor?
Any variation of the charge within a p-n diode with an applied voltage variation yields a capacitance wich must be added to the circuit model of a p-n diode. The capacitance associated with the charge variation in the depletion layer is called the junction capacitance, while the capacitance associated with the excess carriers in the quasi-neutral region is called the diffusion capacitance. Both types of capacitances are non-linear so that we will derive the small-signal capacitance in each case. We will find that the junction capacitance dominates for reverse-biased diodes, while the diffusion capacitance dominates in strongly forward-biased diodes. The total capacitance is the sum of both.
What is the differencebetween a run capacitor and start capacitor?
The run capacitor is used when the load is functional while the start capacitor is used to produce the initial torque to drive the load.
Why is discharging slower than charging in a capacitor filter?
Look closely at the circuit. If discharging is slower than charging, then there must be less current available for discharging. The equation of a capacitor is... dv/dt = i/c which means that the slope of the voltage is proportional to the current and inversely proportional to the capacitance. This does not matter if it is a charging or a discharging situation. For example, one amp of current into one farad of capacitance will be one volt per second, and negative one amp of current into (out of) that same one farad capacitance will be negative one volt per second. You don't give a lot of information in the question, but it sounds like you are analyzing the filter in a rectifier. The charge path is through the diode, which is a low impedance, high current, circuit, while the discharge path is only through the load. This would explain, in one case, why the discharge time is greater than the charge time.
Why was the capacitor discharging current negative?
When a capacitor is discharging, current is flowing out of the capacitor to other elements in the circuit, similar to a battery. Current flowing out of an element, by convention, is defined as negative current, while current flowing into an element, such as a resistor, is defined as positive current. Thus a discharging capacitor will always have a negative current.
Define capacitance with respect to physical structure and electrical function?
capacitance, in electricity, capability of a body, system, circuit, or device for storing electric charge. Capacitance is expressed as the ratio of stored charge in coulombs to the impressed potential difference in volts. The resulting unit of capacitance is the farad [for Michael Faraday]. In an electric circuit the device designed to store charge is called a capacitor. An ideal capacitor, i.e., one having no resistance or inductance, may be spoken of as a capacitance. When an alternating current flows through a capacitor, the capacitor produces a reactance that resists the current (see impedance). While every element of a circuit has some capacitance, it is a goal of good design to reduce such unwanted or stray capacitance to a minimum.
What does NF on a capacitor mean?
While it is possible that the company producing the capacitor is using the NF as an identification tool, usually we would expect nF to specify the capacitance or value of the capacitor. For example, a capacitor with the value of 10nF ought to have a capacitance of about 10 nano Farads. This is equivalent to 10*10-9 Farads.
What does 35V and 1000uF on capacitor specify?
1000 microfarads is its rated capacitance, while 35 volts is its rated voltage.
A circuit contains a 10 pF capacitor and a 50 pF capacitor connected in parallel.What is the total capacitance of this circuit?
When capacitors are connected in parallel, the total capacitance in the circuit in which they are connected is the sum of both capacitances. Capacitors in parallel add like resistors in series, while capacitors in series add like resistors in parallel.
What is the effect of dielectric on the capacitance of a capacitor?
Any variation of the charge within a p-n diode with an applied voltage variation yields a capacitance wich must be added to the circuit model of a p-n diode. The capacitance associated with the charge variation in the depletion layer is called the junction capacitance, while the capacitance associated with the excess carriers in the quasi-neutral region is called the diffusion capacitance. Both types of capacitances are non-linear so that we will derive the small-signal capacitance in each case. We will find that the junction capacitance dominates for reverse-biased diodes, while the diffusion capacitance dominates in strongly forward-biased diodes. The total capacitance is the sum of both.
How do you reduce a ripple voltage?
You reduce ripple voltage by adding a low-pass filter. In the simplest case, you put a capacitor after the rectifier. The peak voltage will be the rectifier output voltage less the forward bias of the rectifier, while the minimum voltage will depend on current and capacitance. In a more complex case, you could use an LC filter, making the peak voltage smaller. Specifics are dependent on the power and performance requirements.
If the voltage applied across a capacitance is triangular in waveform then the waveform of the current?
Depend the value of capacitor. Capacitance in series act like a high pass filter, while in parallel act like low pass filter. By fourier series, triangular wave is combine of series of the sine or cosine waves. Therefore by certain capacitance, sine wave can preduce by applied a triangular signal through a capacitor. Current is just 90 degree shift from voltage, shape is same.
What is the labeling nomenclature for capacitors and how is it used to identify and select capacitors?
Capacitors are marked with the capacitance and the maximum working voltage. The action of a capacitor is store charge short-term and a capacitor is commonly used as a reservoir of charge in a rectifier circuit to smooth the dc output voltage. Other uses in electronic circuits are as a dc-blocker which passes an ac signal while not passing the dc bias, or as a decoupling capacitor in dc circuits to remove any ac signals present while preserving the dc voltage, or in timing circuits because the time-constant of a resistor and a capacitor connected together is CR, or in filters and tuned circuits. Sometimes a variable capacitor is used, connected to a control knob for tuning a radio. In each of the above applications there are accurate methods to decide exactly how much capacitance is required.
What is stray capacitance and how is different from ordinary capacitor?
Any two adjacent conductors can be considered a capacitor, although the capacitance will be small unless the conductors are close together for long. This (often unwanted) effect is termed "stray capacitance". Stray capacitance can allow signals to leak between otherwise isolated circuits (an effect called crosstalk), and it can be a limiting factor for proper functioning of circuits at high frequency. Stray capacitance is often encountered in amplifier circuits in the form of "feedthrough" capacitance that interconnects the input and output nodes (both defined relative to a common ground). It is often convenient for analytical purposes to replace this capacitance with a combination of one input-to-ground capacitance and one output-to-ground capacitance. (The original configuration - including the input-to-output capacitance - is often referred to as a pi-configuration.) Miller's theorem can be used to effect this replacement. Miller's theorem states that, if the gain ratio of two nodes is 1/K, then an impedance of Z connecting the two nodes can be replaced with a Z/(1-k) impedance between the first node and ground and a KZ/(K-1) impedance between the second node and ground. (Since impedance varies inversely with capacitance, the internode capacitance, C, will be seen to have been replaced by a capacitance of KC from input to ground and a capacitance of (K-1)C/K from output to ground.) When the input-to-output gain is very large, the equivalent input-to-ground impedance is very small while the output-to-ground impedance is essentially equal to the original (input-to-output) impedance.
Why it is necessary to connect ceramic disc capacitor across filter capacitor?
The filter capacitor has inductance and is therefore not very responsive to short term transients, i.e. fast rising or falling current edges. The ceramic disk capacitor, on the other hand, has very little inductance, and therefore is very responsive to short term transients. It is normal "best practices" to connect a small ceramic disk capacitor at each IC's Vcc terminal while also using bulk capacitance in the power supply and at various other places. For the same reason, you want a ceramic disc at the main filter capacitor in the power supply.
Why does the run capacitor have a lower MFD rating than the start capacitor?
The run capacitor has to absorb the VARs while the motor is running, but the start capacitor has to provide running current to start the motor. The latter is higher, so more microfarads are needed to pass the greater current. Current in a capacitor is 2pi x frequency x capacitance x voltage so, on a 240 v 50 Hz system, 100 mfd would take 2pi x 50 x 100 x 10-6 x 240 amps, and that is multiplied by the voltage 240 to find the VARs.
What is the differencebetween a run capacitor and start capacitor?
The run capacitor is used when the load is functional while the start capacitor is used to produce the initial torque to drive the load.
