Question 1

Figure 12-4
-The charge of a capacitor is:

Accepted Answer

The charge on a capacitor is stored on both plates, with one plate holding a positive charge and the other holding an equal and opposite negative charge.

Question 2

If the distance between the plates of a capacitor is increased, the capacitance _ .

Accepted Answer

The capacitance of a capacitor decreases as the distance between its plates is increased, according to the formula C = εA/d, where C is the capacitance, ε is the permittivity of the dielectric material between the plates, A is the area of the plates, and d is the distance between the plates.

Question 3

Figure 12-1
-The three capacitors in series in Figure 12-1 have an equivalent value:

Accepted Answer

When capacitors are connected in series, the equivalent capacitance is always less than the smallest individual capacitor in the series. This is because the inverse of the total capacitance is the sum of the inverses of the individual capacitances.

Question 4

Figure 12-1
-The main disadvantage of an electrolytic capacitor is:

Accepted Answer

Electrolytic capacitors are known for their high leakage current compared to other types of capacitors, which can be a significant disadvantage in certain applications where minimal power loss and high stability are required.

Question 5

-Three 2 µF capacitors are connected in parallel. What is the total capacitance?

Accepted Answer

When capacitors are connected in parallel, their capacitances add up. Therefore, the total capacitance is 2 µF + 2 µF + 2 µF = 6 µF.

Question 6

-If the capacitor in Figure 12-3 is 0.1 µF and it is replaced by a 0.47 µF capacitor, which value capacitor will have the higher reactance?

Accepted Answer

The reactance of a capacitor is inversely proportional to its capacitance, meaning that a smaller capacitance results in a higher reactance. Therefore, the 0.1 µF capacitor will have a higher reactance than the 0.47 µF capacitor.

Question 7

Figure 12-1
-Calculate the equivalent capacitance of the three series capacitors in Figure 12-1.

Accepted Answer

The equivalent capacitance, $C_{eq}$, of capacitors in series is given by the reciprocal of the sum of the reciprocals of their capacitances: $\frac{1}{C_{eq}} = \frac{1}{C_1} + \frac{1}{C_2} + \frac{1}{C_3}$. Without the specific values of $C_1$, $C_2$, and $C_3$ from "Figure 12-1", the correct answer cannot be directly calculated here. However, given the options, the process involves calculating the reciprocal of each individual capacitor's value, summing those reciprocals, and then taking the reciprocal of that sum to find $C_{eq}$. The correct choice (B) suggests a scenario where the combined effect of the series capacitors significantly reduces the equivalent capacitance, which is characteristic of capacitors in series.

Question 8

Figure 12-2
-Assuming the capacitors in Figure 12-2 are non-polarized electrolytic capacitors, what is the maximum AC rms voltage that can safely be applied to the circuit?

Accepted Answer

Non-polarized electrolytic capacitors typically have a lower voltage rating compared to polarized ones. A common maximum AC rms voltage for non-polarized electrolytic capacitors is around 24 V.

Question 9

Figure 12-1
-A capacitor rated at 10,000 µF would typically have what kind of dielectric?

Accepted Answer

Aluminum oxide is commonly used as the dielectric in electrolytic capacitors, which often have large capacitance values like 10,000 µF.

Question 10

Figure 12-1
-A capacitor has a capacitance of 0.1 µF with air as the dielectric. If the dielectric material is changed from air to a ceramic material with a dielectric constant of 600, what is the new capacitance? Note: Neither air nor Ceramic capacitors this large are available.)

Accepted Answer

The new capacitance can be calculated using the formula $C_{new} = C_{original} \times \kappa$, where $\kappa$ is the dielectric constant. So, the new capacitance is $0.1 \mu F \times 600 = 60 \mu F$.

Question 11

Figure 12-4
-Given the circuit in Figure 12-4, what is the approximate voltage across the capacitor at the end of 1 second after the 10V source is connected?

Accepted Answer

The voltage across a charging capacitor in an RC circuit after a time t is given by V(t) = V0(1 - e^(-t/RC)), where V0 is the initial voltage, R is resistance, and C is capacitance. After one time constant (t = RC), the voltage is approximately 63% of the source voltage, which is 6.3 V for a 10 V source.

Question 12

A capacitor has a plate area of 0.01 square meters. A second capacitor has a plate area of 0.02 square meters. If the first capacitor is 0.1 µF, what is the value of the second capacitor if all other physical characteristics are identical?

Accepted Answer

The capacitance of a capacitor is directly proportional to its plate area. Doubling the plate area from 0.01 to 0.02 square meters doubles the capacitance from 0.1 µF to 0.2 µF.

Question 13

-A capacitor produces a capacitive reactance of 18.086 kΩ with an applied voltage having a frequency of 400 Hz. What is the capacitor value?

Accepted Answer

The answer of  
-A capacitor produces a capacitive reactance...

Question 14

A discharged capacitor has charges on its plates.

Accepted Answer

A discharged capacitor has no charge on its plates.

Question 15

Figure 12-2
-What is the maximum DC voltage that can safely be applied to the circuit in Figure 12-2?

Accepted Answer

The answer of  Figure 12-2
-What is the maximum DC...

Question 16

-If the capacitor in Figure 12-3 is 0.1 µF and it is replaced by a 0.47 µF capacitor, which value capacitor will cause the higher circuit current?

Accepted Answer

The 0.47 µF capacitor will cause a higher circuit current because in AC circuits, the capacitive reactance (which opposes current flow) decreases as the capacitance increases, allowing more current to flow through the circuit.

Question 17

What would we call a 0.000000000001 F capacitor?

Accepted Answer

1 pF (picofarad) is equivalent to 0.000000000001 F, which is the correct conversion for the given value.

Question 18

One time constant can be solved by:

Accepted Answer

One time constant for an RC (resistor-capacitor) circuit is calculated by multiplying the capacitance (in farads) by the resistance (in ohms). This gives the time constant in seconds, symbolized by τ (tau), where τ = RC.

Question 19

-Calculate the reactance of the capacitor if it has a value 1.0 µF and the frequency is 10 kHz.

Accepted Answer

The answer of  
-Calculate the reactance of the capacitor...

Question 20

Figure 12-2
-Calculate the equivalent value of the parallel capacitors in Figure 12-2.

Accepted Answer

The answer of  Figure 12-2
-Calculate the equivalent value of...

Quiz 12: Capacitors

Figure 12-4 -The charge of a capacitor is:

If the distance between the plates of a capacitor is increased, the capacitance _ .

Figure 12-1 -The three capacitors in series in Figure 12-1 have an equivalent value:

Figure 12-1 -The main disadvantage of an electrolytic capacitor is:

-Three 2 µF capacitors are connected in parallel. What is the total capacitance?

-If the capacitor in Figure 12-3 is 0.1 µF and it is replaced by a 0.47 µF capacitor, which value capacitor will have the higher reactance?

Figure 12-1 -Calculate the equivalent capacitance of the three series capacitors in Figure 12-1.

Figure 12-2 -Assuming the capacitors in Figure 12-2 are non-polarized electrolytic capacitors, what is the maximum AC rms voltage that can safely be applied to the circuit?

Figure 12-1 -A capacitor rated at 10,000 µF would typically have what kind of dielectric?

Figure 12-1 -A capacitor has a capacitance of 0.1 µF with air as the dielectric. If the dielectric material is changed from air to a ceramic material with a dielectric constant of 600, what is the new capacitance? Note: Neither air nor Ceramic capacitors this large are available.)

Figure 12-4 -Given the circuit in Figure 12-4, what is the approximate voltage across the capacitor at the end of 1 second after the 10V source is connected?