Lesson 4: Understanding Capacitance and how it affects a circuit
One picofarad in decimal form is written as ? F.
0.000000000001
One microfarad in decimal form is ? and may be abbreviated ? .
0.000001 F / 1 µF
One picofarad is one farad times ? .
10−12
How long will it take for a 50 µF capacitor to fully charge if it is in a series circuit with a 100 KΩ resistor?
25 seconds
How many time constants are required to charge a capacitor to a level where it is considered to be fully charged?
5
How many time constants for a capacitor to fully discharge?
5
A time constant is the amount of time required to charge a capacitor to ? of the amount left to reach its full charge.
63.2%
? is the letter designation for capacitance.
C
A(n) ? will not hold its charge indefinitely.
Capacitor
The physical structure of a(n) ? consists of two conducting surfaces separated by an insulating material.
Capacitor
When a capacitor of one farad is connected to a source of one volt, its charge is one ?
Coulomb
The unit of capacitance is the farad, abbreviated ? .
F
Electrons flow through a capacitor.
False
The type of dielectric used has no effect on a capacitor.
False
Two conductors feeding a load would not have capacitance.
False
Current can flow only during the period of time that a capacitor is ? .
II. charging IV. discharging
A capacitor has the same area of plates and the same distance between the plates. The capacitance will be ? if air is used instead of insulating oil.
Lower
A picofarad is also called a micromicrofarad and may be abbreviated µµF.
True
An AC ammeter indicates a steady current when it is connected in series with a capacitor across an AC source.
True
Select factors that determine the capacitance of a capacitor.
a.Area of the plates (conducting surfaces) b.Distance between the plates c.The type of dielectric used (insulating material) d.All of the above
If a capacitor is subjected to a voltage in excess of that for which it is designed, the electron flow may puncture the insulation, causing an arc-through, which destroys the ? and, therefore, the capacitor.
dielectric
The ? field is formed when electrons are removed from one plate and deposited on the other.
electrostatic
The term ? refers to the force holding an electrical charge across a capacitor's plates.
electrostatic
One farad ? a practical unit of capacitance.
is not
In a capacitive circuit, the current will ? the voltage by ? .
lead / 90°
When a DC voltage source is connected to a capacitor, electrons will be moved from the plate connected to the ? and deposited on the plate connected to the ? pole. This will continue until the voltage across the capacitor equals the voltage source.
positive / negative
Select the equation to find the time constant for a resistive-capacitive circuit.
t=RxC
When a capacitor is connected in a circuit with a resistor, the amount of time needed to charge the capacitor is determined by the ? .
RC time constant
