Flashcards
Chapter 7 Capacitors
Cards in this deck (47)
- 1How is ac current related to ac voltage in a purely capacitive circuit?AC current leads ac voltage.
- 2The material used between the plates of a capacitor is called its:dielectric material
- 3When is a capacitor fully charged?When the current through the capacitor is the same as when the capacitor is discharged.
- 4A capacitor is constructed of two parallel:conductors
- 5A capacitor stores energy within a dielectric between the conducting plates in the form of:an electric field
- 6As a capacitor is being charged, current flowing into the capacitor will:decrease
- 7As a capacitor is being charged, the voltage across its terminals will:increase
- 8When a circuit consists of a capacitor and a resistor in series with a voltage source, and the voltage across the resistor is zero, than the capacitor is:fully discharge
- 9If a charge capacitor is is disconnected from a circuit, it will:leak the charge
- 10The strength of an electric field at a given point is proportional to the potential difference on the plates and inversely proportional to the:plate separation
- 11The strength of an electric field at a given point is proportional to the potential difference on the plates an inversely proportional to the:plate seperation
- 12For a given charge difference, electrostatic field strength varies according to:plate area
- 13What is the value of a capacitor that can store two coulombs of charge when 500 volts is applied across its plates?4,000 uF
Q/VxC - 14* If the dielectric constant of a capacitor is decreased, than its capacitance will:decrease
* - 15Most older types of paper capacitors have been replaced by which type of construction?plastic film
- 16Capacitor value markings are usually: *Alphanumeric
* - 17After which time constant can a capacitor be considered to be fully charged?fifth
- 18An 8 V power source is charging a capacitor. how many volts will be across the capacitor at the second time constant?7 volts
- 19A capacitor's rate of charge is considered:exponential
- 20A source voltage across a capacitor will:lag the current by 90 degrees
- 21Power stored from the source and than returned to the source is called:reactive pwer
- 22If an open capacitor is checked with an ohmmeter, the needle will:show infinity
- 23What is wrong with a leaky capacitor?The dielectric resistance has decreased.
- 24In a circuit, an output capacitor and a resistor are connected in series with an ac signal. What filter action will be the result?low-pass
- 25In an ac circuit, a capacitor and an out-put resistor are connected in series with an ac signal. What filter action will be the result?hight-pass
- 26A capacitor and an output capacitor resistor from a series circuit with a SQUATE wave applied. The circuit is:a differentiator
- 27A resistor and output capacitor from a series circuit with a square wave applied. The circuit is: *an integrator
* - 28The reactance of a capacitor in a DC circuit is:Infinity
- 29What is the value of a capacitor connected to a 500 kHz AC source that has 1 k ohms of resistance? C=1/2^fXc318pF
- 30What is the value of theta for an AC circuit that consists of a 10 ohm series resistor and a capacitor with a reactance of 15 ohms? TAN(O)=opp/ADJ= -5ohm/10ohm0=TAN-1(-15/10)=-56.3deg.
- 31Power that is stored from a source and than return to the source is called:reactive power
- 32**Power that is measured in voltage-amperes is called:apparent power
- 33If the reactive power of a circuit is 50 mw, while the apparent power is 64 mw, than what is the true power of the circuit? Pt=sqr/(Pa)sq-(Pr)sqsqr(.064)sq-(.050)sq= 40mw
- 34What is the power factor if the apparent power of a circuit is 5 w, while the true power is 4 W? P.F.=Cos(0)= Pt/Pa= 4W/5W=0.8
- 35What is the capacitive reactance? 1v, 15kHz, 3.3uf Xc=1/2^fc 1/ 2^(150000Hz)(3.3)(10)-6F=?1/xXc = 3.2 ohms
- 36**If the dielectric strength of a capacitor is decreased, than its capacitance will:decrease
- 37?**In a 29 V Ac series RC circuit, if 20 volts is read across the resistor and 40 volts is measured across the capacitor, the applied voltage is:?45 volts
50 volts
55 volts
60 volts - 38?**What is the impedance of a 60 Hz, 2 V AC circuit that consists of a 22uf capacitor, and a 100 ohm resistor connected in parallel?*180 ohms
62.7 ohms
44.6 ohms
128 ohms - 39**A capacitor rate of charge is consider:exponential
- 40**Power that is measured in volt-amperes is call:apparent power
- 41?**What is the total current in a Parallel circuit consisting of a 1.27 uf capacitor, and a 50 ohm resistor, with a 2.5 kHz, 10 V AC supply?400 mA
- 42?**Power that is measured in volt-amperes is called:apparent power
- 43**What is the total current in a parallel circuit consisting of a 1.27 uf capacitor, and resistor, and a 50 ohm resistor, with a 2.5 Khz, 10 V AC supply?400MA
- 44When a good capacitor is ohmeter checked with a DDM, the bar graph display will:Show infinity
- 45?**If a 500 UF capacitor has stored 2 coulombs of charge, than what is the voltage across the capacitor?? 250 uv
1 mv
1 kv
4 kv - 46? What is the time to charge the capacitor? series: 12 v, R1 11ohm, C1 ?12 ms
10 ms
7 ms
? 5 ms - 47?**What is the capacitive reactance,of a 4.5 uf capacitor connected to a 1 khz ac source?4.7 ohms
34 ohms
29.5 ohms
? 213 ohms
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- Flashcards on Chapter 7 Capacitors, created by pete.c.diaz on 26/04/2014.
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