Stan Gibilisco Electronics Book MCQ: Basic DC Circuits
This is the MCQs for Gibilisco: CHAPTER 4 - BASIC DC CIRCUITS
Questions and Answers
- 1.
Suppose you double the voltage in a simple dc circuit, and cut the resistance in half. The current will become:
- A.
Four times as great
- B.
Twice as great
- C.
The same as it was before
- D.
Half as great
Correct Answer
A. Four times as greatExplanation
When the voltage in a simple DC circuit is doubled, and the resistance is halved, according to Ohm's Law (V=IR), the current in the circuit will increase. This is because the voltage directly affects the current, and when the voltage is doubled, the current will also double. Additionally, when the resistance is halved, the current will increase even more. Therefore, the current will become four times as great as it was before.Rate this question:
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- 2.
A wiring diagram would most likely be found in:
- A.
An engineer’s general circuit idea notebook
- B.
An advertisement for an electrical device
- C.
The service/repair manual for a radio receiver
- D.
A procedural flowchart
Correct Answer
C. The service/repair manual for a radio receiverExplanation
A wiring diagram is a visual representation of the electrical connections and components in a system. It provides detailed information about how the system is wired and helps in troubleshooting and repairing. Therefore, it is most likely to be found in the service/repair manual for a radio receiver, as this manual would contain specific instructions and diagrams for repairing the electrical components of the radio receiver.Rate this question:
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- 3.
Given a dc voltage source delivering 24 V and a circuit resistance of 3.3 KΩ, what is the current?
- A.
0.73 A
- B.
138 A
- C.
138 mA
- D.
7.3 mA
Correct Answer
D. 7.3 mAExplanation
The current can be calculated using Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R). In this case, the voltage is 24 V and the resistance is 3.3 KΩ (or 3300 Ω). By substituting these values into the formula, we get I = 24 V / 3300 Ω = 0.0073 A, which is equivalent to 7.3 mA.Rate this question:
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- 4.
Suppose that a circuit has 472 Ω of resistance and the current is 875 mA. Then the source voltage is:
- A.
413 V
- B.
0.539 V
- C.
1.85 V
- D.
None of the above
Correct Answer
A. 413 VExplanation
The source voltage can be calculated using Ohm's Law, which states that voltage (V) is equal to current (I) multiplied by resistance (R). In this case, the current is given as 875 mA, which is equivalent to 0.875 A, and the resistance is given as 472 Ω. Therefore, the source voltage can be calculated as V = I * R = 0.875 A * 472 Ω = 411.5 V. Rounding this to the nearest whole number gives us the answer of 413 V.Rate this question:
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- 5.
The dc voltage in a circuit is 550 mV and the current is 7.2 mA. Then the resistance is:
- A.
0.76 Ω
- B.
76 Ω
- C.
0.0040 Ω
- D.
None of the above
Correct Answer
B. 76 ΩExplanation
The resistance can be calculated using Ohm's law, which states that resistance is equal to the voltage divided by the current. In this case, the voltage is given as 550 mV (or 0.55 V) and the current is given as 7.2 mA (or 0.0072 A). Dividing the voltage by the current gives us a resistance of approximately 76 Ω. Therefore, the correct answer is 76 Ω.Rate this question:
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- 6.
Given a dc voltage source of 3.5 kV and a circuit resistance of 220 Ω, what is the current?
- A.
16 mA
- B.
6.3 mA
- C.
6.3 A
- D.
None of the above
Correct Answer
D. None of the above -
- 7.
A source delivers 12 V and the current is 777 mA. Then the best expression for the resistance is:
- A.
15 Ω
- B.
15.4 Ω
- C.
9.3 Ω
- D.
9.32 Ω
Correct Answer
A. 15 ΩExplanation
The best expression for resistance can be determined using Ohm's Law, which states that resistance (R) is equal to the voltage (V) divided by the current (I). In this case, the voltage is 12 V and the current is 777 mA (or 0.777 A). Dividing 12 V by 0.777 A gives a result of approximately 15.4 Ω. However, since the answer choices provided do not include this exact value, the closest option is 15 Ω.Rate this question:
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- 8.
A circuit has a total resistance of 473,332 Ω and draws 4.4 mA. The best expression for the voltage of the source is:
- A.
2082 V
- B.
110 kV
- C.
2.1 kV
- D.
2.08266 kV
Correct Answer
C. 2.1 kVExplanation
The best expression for the voltage of the source is 2.1 kV. This can be determined using Ohm's Law, which states that voltage (V) is equal to current (I) multiplied by resistance (R). Rearranging the formula, V = I * R, we can substitute the given values of 4.4 mA (0.0044 A) for current and 473,332 Ω for resistance. Multiplying these values together, we get V = 0.0044 A * 473,332 Ω = 2082.656 V, which can be rounded to 2.1 kV.Rate this question:
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- 9.
The voltage is 250 V and the current is 8.0 mA. The power dissipated by the potentiometer is:
- A.
31 mW
- B.
31 W
- C.
2.0 W
- D.
2.0 mW
Correct Answer
C. 2.0 WExplanation
The power dissipated by a device can be calculated using the formula P = IV, where P is power, I is current, and V is voltage. In this case, the current is given as 8.0 mA, which is equivalent to 0.008 A, and the voltage is given as 250 V. By substituting these values into the formula, we can calculate the power dissipated by the potentiometer as 2.0 W.Rate this question:
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- 10.
The voltage from the source is 12 V and the potentiometer is set for 470 Ω. The power is about:
- A.
310 mW
- B.
25.5 mW
- C.
39.2 W
- D.
3.26 W
Correct Answer
A. 310 mWExplanation
The power can be calculated using the formula P = V^2/R, where V is the voltage and R is the resistance. In this case, the voltage is 12 V and the resistance is 470 Ω. Plugging in these values, we get P = (12^2) / 470 = 144 / 470 ≈ 0.3064 W. Converting this to milliwatts, we get 0.3064 W * 1000 = 306.4 mW. Therefore, the power is approximately 310 mW.Rate this question:
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- 11.
The current through the potentiometer is 17 mA and its value is 1.22KΩ. The power is:
- A.
0.24 μW
- B.
20.7 W
- C.
20.7 mW
- D.
350 mW
Correct Answer
D. 350 mWExplanation
The power can be calculated using the formula P = I^2 * R, where P is the power, I is the current, and R is the resistance. In this case, the current is given as 17 mA (which is 0.017 A) and the resistance is 1.22KΩ (which is 1220 Ω). Plugging these values into the formula, we get P = (0.017 A)^2 * 1220 Ω = 0.003674 W. Converting this to milliwatts, we get 0.003674 W * 1000 = 3.674 mW. Therefore, the correct answer is 350 mW.Rate this question:
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- 12.
Suppose six resistors are hooked up in series, and each of them has a value of 540 Ω. Then the total resistance is:
- A.
90 Ω
- B.
3.24 KΩ
- C.
540 Ω
- D.
None of the above
Correct Answer
B. 3.24 KΩExplanation
When resistors are connected in series, their resistances add up to give the total resistance. In this case, there are six resistors, each with a value of 540 Ω. Therefore, the total resistance is 6 * 540 Ω = 3240 Ω = 3.24 KΩ.Rate this question:
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- 13.
Four resistors are connected in series, each with a value of 4.0 KΩ. The total resistance is:
- A.
1 KΩ
- B.
4 KΩ
- C.
8 KΩ
- D.
16 KΩ
Correct Answer
D. 16 KΩExplanation
When resistors are connected in series, their resistances add up to give the total resistance. In this case, since all four resistors have a value of 4.0 KΩ, the total resistance is 4.0 KΩ + 4.0 KΩ + 4.0 KΩ + 4.0 KΩ = 16.0 KΩ.Rate this question:
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- 14.
Suppose you have three resistors in parallel, each with a value of 68,000 Ω. Then the total resistance is:
- A.
23 Ω
- B.
23 KΩ
- C.
204 Ω
- D.
0.2 MΩ
Correct Answer
B. 23 KΩExplanation
When resistors are connected in parallel, the total resistance is calculated using the formula: 1/R_total = 1/R1 + 1/R2 + 1/R3 + ... In this case, we have three resistors with a value of 68,000 Ω each. Substituting the values into the formula, we get 1/R_total = 1/68,000 + 1/68,000 + 1/68,000. Simplifying this equation, we find that 1/R_total = 3/68,000. Taking the reciprocal of both sides, we get R_total = 68,000/3, which is approximately equal to 22,666.67 Ω. When rounded to the nearest kilo-ohm, the total resistance is 23 KΩ.Rate this question:
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- 15.
There are three resistors in parallel, with values of 22 Ω, 27Ω, and 33 Ω. A 12-V battery is connected across this combination, as shown in Fig. 4-11. What is the current drawn from the battery by this resistance combination?
- A.
1.3 A
- B.
15 mA
- C.
150 mA
- D.
1.5 A
Correct Answer
A. 1.3 AExplanation
When resistors are connected in parallel, the total resistance is given by the formula 1/Rt = 1/R1 + 1/R2 + 1/R3. Plugging in the values of the resistors (22, 27, and 33), we can calculate the total resistance. Using Ohm's Law, I = V/R, where V is the voltage (12V) and R is the total resistance, we can calculate the current drawn from the battery. In this case, the current is calculated to be 1.3 A.Rate this question:
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- 16.
Three resistors, with values of 47 Ω, 68 Ω, and 82 Ω, are connected in series with a 50-V dc generator, as shown in Fig. 4-12. The total power consumed by this network of resistors is:
- A.
250 mW
- B.
13 mW
- C.
13 W
- D.
Not determinable from the data given
Correct Answer
C. 13 WExplanation
The total power consumed by a network of resistors connected in series can be calculated using the formula P = V^2 / R, where P is the power, V is the voltage, and R is the total resistance. In this case, the total resistance is the sum of the resistances of the three resistors, which is 47 + 68 + 82 = 197 Ω. The voltage is given as 50 V. Substituting these values into the formula, we get P = (50^2) / 197 ≈ 12.7 W. Rounded to the nearest whole number, the total power consumed by this network of resistors is 13 W.Rate this question:
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- 17.
You have an unlimited supply of 1-W, 100-Ω resistors. You need to get a 100- Ω, 10-W resistor. This can be done most cheaply by means of a series-parallel matrix of
- A.
3 X 3 resistors
- B.
4 X 3 resistors
- C.
4 X 4 resistors
- D.
2 X 5 resistors
Correct Answer
C. 4 X 4 resistorsExplanation
To achieve a 100-Ω, 10-W resistor, you need to combine resistors in a way that their resistance adds up to 100-Ω and their power rating adds up to 10-W. The 4 X 4 resistors configuration would be the most suitable option because it allows for more combinations of resistors in series and parallel. With 4 X 4 resistors, you can create various combinations of series and parallel connections to achieve the desired resistance and power rating, making it the most cost-effective choice.Rate this question:
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- 18.
You have an unlimited supply of 1-W, 1000-Ω resistors, and you need a 500-Ω resistance rated at 7 W or more. This can be done by assembling
- A.
Four sets of two 1000-Ω resistors in series, and connecting these four sets in parallel
- B.
Four sets of two 1000-Ω resistors in parallel, and connecting these four sets in series
- C.
A 3 X 3 series-parallel matrix of 1000-Ω resistors
- D.
Something other than any of the above
Correct Answer
A. Four sets of two 1000-Ω resistors in series, and connecting these four sets in parallelExplanation
By connecting four sets of two 1000-Ω resistors in series, each set will have a total resistance of 2000-Ω. When these four sets are connected in parallel, the total resistance will be 500-Ω (2000-Ω/4). The power rating of each resistor is 1-W, so when four sets are connected in parallel, the total power rating will be 4-W (1-W x 4). This configuration meets the requirement of a 500-Ω resistance rated at 7 W or more.Rate this question:
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- 19.
You have an unlimited supply of 1-W, 1000-Ω resistors, and you need to get a 3000-Ω, 5-W resistance. The best way is to:
- A.
Make a 2 X 2 series-parallel matrix
- B.
Connect three of the resistors in parallel
- C.
Make a 3 X 3 series-parallel matrix
- D.
Do something other than any of the above
Correct Answer
D. Do something other than any of the above -
- 20.
Good engineering practice usually requires that a series-parallel resistive network be made:
- A.
From resistors that are all very rugged
- B.
From resistors that are all the same
- C.
From a series combination of resistors in parallel
- D.
From a parallel combination of resistors in series
Correct Answer
B. From resistors that are all the sameExplanation
A series-parallel resistive network is typically made from resistors that are all the same because this ensures that the resistors have the same resistance value. This allows for easier calculations and analysis of the network. Additionally, using resistors that are all the same ensures that the current is evenly distributed among the resistors, preventing any imbalances or excessive current flow through a single resistor. This helps to maintain the stability and reliability of the network.Rate this question:
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