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33 Cards in this Set
- Front
- Back
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If circuit voltage is held constant, circuit current will react in what manner as the resistance (a) increases, and (b) decreases? |
(a) Decrease (b) increase |
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If circuit resistance is held constant, circuit current will react in what manner as the voltage (a) increases, and (b) decreases?
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(a) Increase (b) decrease
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According to Ohm's law, what formula should be used to calculate circuit voltage if resistance and current value are known? |
E=IR
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Which of the following terms applies to the rate at which an electrical force causes motion?
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Power
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Which of the following circuit quantities can be varied ONLY by varying one of the other circuit quantities?
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Current
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Which of the following is a correct formula for determining power in an electrical circuit?
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- P=EI
- P=IIR - P=EE/R |
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What is the current in a circuit with 15 ohms of resistance that uses 135 watts of power?
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3 A
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What is the total power used by a 15-ohm resistor with 4 amps of current?
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240 W
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What type of resistor should be used for resistors with power ratings over 5 W?
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Wirewound
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How much total energy is converted by a l-horsepower motor in 10 hours?
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7.46 kWh
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If the energy used by a 7.46 kWh motor is 9.5 kWh, what is the efficiency of the motor?
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.785
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When Kirchoff's voltage law is used to assign polarities to the voltage drop across a resistor, which of the following references is used to indicate the end of the resistor that the current enters?
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Negative
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Which of the following terms applies to a circuit in which there is NO complete path for current?
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Open
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A circuit in which the resistance is almost zero ohms is referred to by which of the following terms?
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Short
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Maximum power is transferred from a source to a load when the value of the load resistance is of what value when compared to the source resistance?
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Equal
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When maximum power is transferred from a source to a load, what is the efficiency of power transfer?
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50%
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A circuit consists of three resistors
connected in parallel. R1 = 30 ohms, R2 = 15 ohms, and R 3 = 10 ohms. If the current through R2 = 4 amperes, what is the total source voltage? |
60 V
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What is the relationship of total current to the current through a component in (a) a series circuit, and (b) a parallel circuit?
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(a) Equals (b) divides
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If a current has a negative polarity when
Kirchoff's current law is applied, which of the following, statements is true of the current? |
It is leaving a junction
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Three equal resistors are connected in parallel and each resistor has an ohmic value of 300 ohms. What is the equivalent resistance of the circuit?
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100
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Three resistors with ohmic values of 120 ohms, 60 ohms, and 40 ohms are
connected in parallel. What is the equivalent resistance of the circuit? |
10
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Two resistors with ohmic values of 90 ohms and 45 ohms are connected in parallel. What is the equivalent resistance of the circuit?
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30
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Which of the following terms describes a single resistor that represents a complex circuit?
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Equivalent resistor
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If an open occurs in a series portion of a circuit, what is the effect on (a) total resistance, and (b) total current?
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(a) Becomes infinite (b) Becomes infinite
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If an open occurs in a parallel branch of a circuit, what is the effect on (a) total resistance, and (b) total current?
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(a) Increases (b) decreases
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If a short circuit occurs in a series portion
of a circuit, what is the effect on (a) total resistance, and (b) total current? |
(a) Decreases (b) increases
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If a short circuit occurs in a parallel branch of a circuit, what is the effect in (a) total resistance, and (b) total current?
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(a) Increases (b) increases
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If one branch of a parallel network shorts, what portion of the circuit current, if any, will flow through the remaining branches?
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An amount determined by the combined resistance of the remaining branches
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Which of the following circuit quantities need NOT be known before designing a voltage divider?
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The voltage of the source
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A single voltage divider provides both negative and positive voltages from a
single source voltage through the use of a _____. |
ground between two of the dividing resistors
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Which of the following voltages are considered dangerous?
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All voltages
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If you discover a possible malfunction in an electric circuit, which of the following actions should be taken?
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Report the malfunction to a qualified technician
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If a person has stopped breathing and there is NO detectable heartbeat, who should perform CPR? |
The first person on the scene |
