How does capacitance affect current

To put this relationship between voltage and current in a capacitor in calculus terms, the current through a capacitor is the derivative of the voltage across the capacitor with respect to time. As a result, inductors always oppose a change in current and thus current lags voltage in inductor.

Where as opposite is case of capacitor that is opposing of rate of rise of voltage. In an inductor the CEMF is responsible for the current to be lagging with the voltage. Capacitor Circuit Characteristics Pure capacitive circuit waveforms. Remember, the current through a capacitor is a reaction against the change in voltage across it.

Power Factor is the ratio of active power to apparent power in an AC circuit. Leading power factor is a term which is used where the load current leads the supply voltage whereas lagging power factor is a term which is used where the load current lags behind the supply voltage. Improving the PF can maximize current-carrying capacity, improve voltage to equipment, reduce power losses, and lower electric bills.

Large 3-phase motors are more efficient than smaller 3-phase motors and most all single phase motors. The main cause of low Power factor is Inductive Load. A negative power factor occurs when the device which is normally the load generates power, which then flows back towards the source. In an electric power system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred.

When the capacitor is fully charged means that the capacitor maintains the constant voltage charge even if the supply voltage is disconnected from the circuit. In the case of ideal capacitors the charge remains constant on the capacitor but in the case of general capacitors the fully charged capacitor is slowly discharged because of its leakage current. When the switch is moved to the position B, then the capacitor slowly discharges by switching on the lamp which is connected in the circuit.

Finally it is fully discharged to zero. The lamp glows brightly initially when the capacitor is fully charged, but the brightness of the lamp decreases as the charge in the capacitor decreases.

Now let us calculate the charge of a capacitor in the above circuit,we know that, the equation for the charge of a capacitor is. The current i flowing through any electrical circuit is the rate of charge Q flowing through it with respect to time. But the charge of a capacitor is directly proportional to the voltage applied through it. The relation between the charge, current and voltage of a capacitor is given in the below equation.

From this relation we observed that the current flowing through the capacitor in the circuit is the product of the capacitance and the rate of change of voltage applied to the circuit. The current flowing through the capacitor is directly proportional to the capacitance of a capacitor and the rate of voltage.

Larger the current, higher is the capacitance of the circuit and higher the applied voltage,larger the current flowing through the circuit. If voltage is constant then charge is also constant. Thus there is no flow of charge. Hence the current flowing through the circuit will become zero.

Josiah Latimer Clark in the year of first used the termFarad. Farad is a standard unit of the capacitance. This is an extremely a large unit for the capacitance. One farad of capacitance is defined as the capacitance with one coulomb of charge which operates at the voltage of one volt. Now capacitors are available with large capacitance values of hundreds of farads. These capacitors are utilizing large surface area to deliver high energy because these have high capacitance values.

At low voltage, super capacitors have the ability to store high energy with high capacitance values. These high energy super capacitors are used in hand held portable devices to replace large, heavy and expensive lithium type capacitors, because they store high energy, like batteries.

These capacitors are also used in audio and video systems in vehicles by replacing the high batteries. The standard unit of capacitance is farad. But this is generally a large unit for the measurement of capacitance. This farad has some sub units; they are micro-farads uF , nano-farads nF and pico-farads pF. Notify me of new posts by email. Electrical Technology 0 2 minutes read.

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