1.
Capacitance acts to store electrical energy as
Correct Answer
D. An electric field
Explanation
Capacitance acts to store electrical energy as an electric field. When a voltage is applied across a capacitor, it creates an electric field between its plates. This electric field stores the electrical energy in the form of potential energy. The amount of energy stored is directly proportional to the capacitance value of the capacitor. Therefore, the correct answer is an electric field.
2.
As capacitor plate area increases, all other things being equal,
Correct Answer
A. The capacitance increases
Explanation
As the capacitor plate area increases, all other things being equal, the capacitance increases. This is because the capacitance of a capacitor is directly proportional to the area of its plates. A larger plate area provides more surface area for the electric field to interact with, resulting in a higher capacitance.
3.
As the spacing between plates in a capacitor is made smaller, all other things being equal,
Correct Answer
A. The capacitance increases
Explanation
The capacitance of a capacitor is directly proportional to the area of the plates and inversely proportional to the distance between them. As the spacing between plates in a capacitor is made smaller, the distance between the plates decreases, resulting in an increase in capacitance. This is because the closer the plates are, the stronger the electric field between them, allowing for more charge to be stored on the plates. Therefore, the capacitance increases.
4.
A material with a high dielectric constant
Correct Answer
A. Acts to increase capacitance per unit volume
Explanation
A material with a high dielectric constant acts to increase capacitance per unit volume because it increases the ability of the material to store electrical energy in an electric field. The dielectric constant represents the material's ability to polarize in response to an applied electric field. When a high dielectric constant material is placed between the plates of a capacitor, it enhances the electric field, resulting in a higher capacitance value. This is because the increased polarization of the material allows for more charge to be stored per unit volume, increasing the capacitance.
5.
A capacitance of 100 pF is the same as which of the following?
Correct Answer
C. 0.0001 µF
Explanation
A capacitance of 100 pF is equivalent to 0.0001 µF because there are 1000 picofarads (pF) in 1 nanofarad (nF), and there are 1000 nanofarads (nF) in 1 microfarad (µF). Therefore, to convert from pF to µF, we divide by 1000 twice, resulting in 0.0001 µF.
6.
A capacitance of 0.033 µF is the same as which of the following?
Correct Answer
D. 33,000 pF
Explanation
The given capacitance of 0.033 µF can be converted to picofarads (pF) by multiplying it by 1,000,000. Therefore, 0.033 µF is equal to 33,000 pF.
7.
If five 0.050-µF capacitors are connected in parallel, what is the net capacitance of the combination?
Correct Answer
B. 0.25 µF
Explanation
When capacitors are connected in parallel, the total capacitance is the sum of the individual capacitances. Therefore, when five 0.050-µF capacitors are connected in parallel, the net capacitance of the combination is 0.050 µF + 0.050 µF + 0.050 µF + 0.050 µF + 0.050 µF = 0.25 µF.
8.
If five 0.050-µF capacitors are connected in series, what is the net capacitance of the
combination?
Correct Answer
A. 0.010 µF
Explanation
When capacitors are connected in series, the reciprocal of the net capacitance is equal to the sum of the reciprocals of the individual capacitances. In this case, the reciprocal of the net capacitance is equal to the sum of the reciprocals of the five 0.050 μF capacitors. Calculating this, we get:
1/net capacitance = 1/0.050 + 1/0.050 + 1/0.050 + 1/0.050 + 1/0.050
1/net capacitance = 20 + 20 + 20 + 20 + 20
1/net capacitance = 100
Taking the reciprocal of both sides, we find that the net capacitance is 1/100, which simplifies to 0.010 μF. Therefore, the correct answer is 0.010 μF.
9.
Two capacitors, C1 and C2, are connected in series, with capacitances of 4 microfarads and 6 microfarads, respectively. What is the equivalent capacitance of the combination?
Correct Answer
B. 2.4 microfarads
10.
Suppose that two capacitors are in parallel. Their values are 47.0 pF and 470 µF. What is thenet capacitance of this combination?
Correct Answer
D. 470 µF
Explanation
When capacitors are connected in parallel, the total capacitance is the sum of the individual capacitances. In this case, the two capacitors have values of 47.0 pF and 470 µF. Since the values are in different units, they need to be converted to the same unit before adding. Converting 47.0 pF to µF, we get 0.047 µF. Adding this to the value of 470 µF gives a total capacitance of 470.047 µF, which is closest to 470 µF. Therefore, the correct answer is 470 µF.
11.
Suppose that three capacitors are in parallel. Their values are 0.0200 µF, 0.0500 µF, and0.10000 µF. What is the net capacitance of this combination?
Correct Answer
B. 0.1700 µF
Explanation
When capacitors are connected in parallel, the total capacitance is equal to the sum of the individual capacitances. In this case, the net capacitance is equal to 0.0200 µF + 0.0500 µF + 0.1000 µF = 0.1700 µF.
12.
The main advantage of air as a dielectric material for capacitors is the fact that it
Correct Answer
C. Has low loss
Explanation
Air has low loss as a dielectric material for capacitors. This means that it has a very low amount of energy loss when used as a dielectric, resulting in high efficiency. This is advantageous because it allows for better performance and less energy wastage in the capacitor.
13.
Which of the following is not a characteristic of mica capacitors?
Correct Answer
B. Small size, even for large values of capacitance
Explanation
Mica capacitors are known for their excellent efficiency, high voltage-handling capacity, and low loss. However, they are not characterized by small size, especially when it comes to large values of capacitance. Mica capacitors tend to be larger in size compared to other types of capacitors, making them less suitable for applications where space is limited.
14.
Which of the following capacitance values is most typical of a disk-ceramic capacitor?(a) 100 pF
Correct Answer
A. 100 pF
Explanation
A disk-ceramic capacitor is a type of capacitor that is commonly used in electronic circuits for its small size and high capacitance value. It is typically used for filtering and decoupling applications. The most typical capacitance value for a disk-ceramic capacitor is 100 pF, as it provides a good balance between size and capacitance. Capacitance values of 33 µF, 470 µF, and 10,000 µF are much larger and would be more suitable for applications that require higher capacitance values.
15.
Which of the following capacitance values is most typical of a paper capacitor?
Correct Answer
B. 0.01 µF
Explanation
A paper capacitor is a type of capacitor that uses paper as the dielectric material. Paper capacitors are commonly used in low voltage and low frequency applications. The most typical capacitance value for a paper capacitor is 0.01 µF, which is also known as 10,000 pF. This value is suitable for filtering and coupling applications in electronic circuits. Capacitance values of 0.001 pF and 100 µF are not typical for paper capacitors, as they are either too small or too large for this type of capacitor. 3300 µF is a very large capacitance value and is typically used in applications that require high energy storage, such as power supply filtering.
16.
Which of the following capacitance ranges is most typical of an air-variable capacitor?
Correct Answer
C. 1 pF to 100 pF
Explanation
An air-variable capacitor is a type of capacitor that uses air as the dielectric material. Air-variable capacitors typically have capacitance values in the range of 1 pF to 100 pF. This range is considered most typical because it covers a wide range of values that are commonly used in electronic circuits. Capacitance values in the range of 1 pF to 100 pF are suitable for applications such as tuning circuits, filters, and impedance matching.
17.
Which of the following types of capacitors is polarized?
Correct Answer
D. Electrolytic
Explanation
Electrolytic capacitors are polarized because they have a positive and negative terminal, meaning they can only be connected in a specific direction. This is due to the presence of an electrolyte inside the capacitor, which allows for the flow of current in one direction. In contrast, paper, mica, and interelectrode capacitors are non-polarized and can be connected in either direction.
18.
If a capacitor has a negative temperature coefficient, then
Correct Answer
A. Its capacitance decreases as the temperature rises
Explanation
A capacitor with a negative temperature coefficient means that its capacitance decreases as the temperature rises. This is because as the temperature increases, the molecules in the dielectric material of the capacitor gain more energy and move more rapidly. This increased movement disrupts the alignment of the molecules, reducing the overall capacitance of the capacitor. Therefore, as the temperature rises, the capacitance of the capacitor decreases.
19.
Suppose that a capacitor is rated at 33 pF 10%. Which of the following actual capacitancevalues is outside the acceptable range?
Correct Answer
B. 37 pF
Explanation
The given capacitor is rated at 33 pF with a tolerance of 10%. This means that the actual capacitance can vary by 10% of 33 pF, which is 3.3 pF. Therefore, the acceptable range for the actual capacitance is between 29.7 pF (33 pF - 3.3 pF) and 36.3 pF (33 pF + 3.3 pF). Among the given options, 37 pF is outside this range, making it the answer.
20.
Suppose that a capacitor, rated at 330 pF, shows an actual value of 317 pF. By how manypercent does its actual capacitance differ from its rated capacitance?
Correct Answer
B. −3.9%
Explanation
The actual capacitance of the capacitor is 317 pF, which is 13 pF less than the rated capacitance of 330 pF. To find the percentage difference, we divide the difference by the rated capacitance and multiply by 100. So, (13/330) * 100 = 3.9%. Therefore, the actual capacitance differs from the rated capacitance by -3.9%.