What is the equivalent inductance of a 4 H inductor in series with a parallel combination of a 3 H, 6 H, and 2 H inductor?

Correct answer: 5 H

Explanation

This is a two-step problem for combining inductors, based on Example 3.9. First, the rule for parallel inductors is applied, and then the result is combined with the series inductor using the rule for series combination.

Other questions

Question 1

In the context of a capacitor, what is the relationship between the stored charge q, the capacitance C, and the voltage v between the plates in an ideal capacitor?

Question 2

What is the current i(t) flowing through a capacitor with capacitance C, as a function of the voltage v(t) across it, assuming the passive configuration?

Question 3

How does an ideal capacitor behave in a circuit with a steady DC voltage after transients have settled?

Question 4

Three capacitors with values C1, C2, and C3 are connected in parallel. What is the equivalent capacitance, Ceq, of this combination?

Question 5

What is the equivalent capacitance for three capacitances connected in series?

Question 6

A parallel-plate capacitor has rectangular plates of 10 cm by 20 cm, separated by an air dielectric with a thickness of 0.1 mm. The dielectric constant of vacuum is approximately 8.85 x 10^-12 F/m, and the relative dielectric constant for air is 1.00. What is the capacitance?

Question 7

What is a key characteristic of electrolytic capacitors that distinguishes them from many other types, such as those with polyethylene or Mylar dielectrics?

Question 8

A capacitor C1 is charged to 100 V and has a capacitance of 1 microfarad. It is then connected at t=0 to an uncharged capacitor C2, also of 1 microfarad. What is the total stored energy in the two capacitors after the switch is closed?

Question 9

For an ideal inductor, what is the relationship between the voltage v(t) across it and the current i(t) flowing through it, assuming the passive reference configuration?

Question 10

What is the formula for the energy w(t) stored in an inductor with inductance L and current i(t)?

Question 11

A current through a 5 H inductance is shown in a waveform that ramps linearly from 0 A to 3 A in 2 seconds, stays at 3 A for 2 seconds, and then ramps linearly from 3 A down to 0 A in 1 second. What is the voltage across the inductor between t=4s and t=5s?

Question 12

How are inductances combined when they are in series?

Question 13

What is the primary purpose of using laminations for the cores of practical inductors?

Question 14

In a pair of mutually coupled inductors, what is the purpose of the dot convention?

Question 15

In the circuit model for a real capacitor shown in Figure 3.14, what does the parallel resistance Rp represent?

Question 16

What is the equivalent inductance of a 3 H, 6 H, and 2 H inductor connected in parallel?

Question 17

The charge on a 2 microfarad capacitor is given by q(t) = 10^-6 sin(10^5 t) C. What is the expression for the current, i(t)?

Question 18

The voltage across a 150 microHenry inductance is a triangular waveform that ramps from 0 to 15 V in 2 microseconds, then ramps from 15 V to -15 V between 2 and 4 microseconds. What is the value of the current i(t) at t=2 microseconds, assuming i(0)=0?

Question 19

What does the fluid-flow analogy for an inductor represent?

Question 20

What is the equivalent capacitance of a 12 microfarad and a 24 microfarad capacitor connected in series?

Question 21

What is the physical unit of inductance?

Question 22

What must be true for the current i(t) in an inductor as long as the voltage v(t) across it is finite?

Question 23

Two inductors, L1 = 1 H and L2 = 2 H, are mutually coupled with M = 1 H. The currents are i1(t) = sin(10t) and i2(t) = 0.5 sin(10t). Both currents are referenced into the dotted terminals. What is the voltage v1(t)?

Question 24

In the circuit model for a real inductor, what does the parallel capacitance Cp, also known as interwinding capacitance, represent?

Question 25

A voltage waveform v(t) shown in Figure 3.6(a) is applied to a 10 microfarad capacitor. The voltage ramps from 0 to 1000V in 1s, is constant at 1000V from 1s to 3s, and ramps from 1000V to 0 in 2s (from t=3s to t=5s). What is the current i(t) from t=0 to t=1s?

Question 27

A 1 microfarad capacitor is being designed. If the dielectric is polyester (relative dielectric constant = 3.4) with a thickness of 15 micrometers, and the plates have a width of 2 cm, what is the required length L of the plates?

Question 28

According to the text, what is a dielectric material?

Question 29

Two capacitances of 2 microfarads and 1 microfarad are connected in series. What is their equivalent capacitance?

Question 30

What is the primary trade-off mentioned in the text regarding the design of practical capacitors for compact electronic circuits?

Question 31

In a pair of mutually coupled inductors where one current is referenced into a dotted terminal and the other is referenced out of a dotted terminal, what is the sign of the mutual inductance term in the voltage equations?

Question 32

An initial charge q(0) is known for a capacitor C, and a current i(t) flows into it starting at t=0. Which equation correctly gives the voltage v(t) across the capacitor for t > 0?

Question 33

What are ferrites, and why are they sometimes used for the cores of inductors?

Question 34

In the context of the MATLAB Symbolic Toolbox described in Section 3.8, what is its primary function for analyzing circuits with inductors and capacitors?

Question 35

What happens to the total stored energy in the circuit of Example 3.6 when the switch closes, connecting a 1 microfarad capacitor charged to 100V to an identical uncharged capacitor?

Question 36

The current through a 10 mH inductor is i(t) = 0.1 cos(10^4 t) A. What is the expression for the stored energy, w(t)?

Question 37

How do capacitances in parallel combine, and how does this compare to the rule for resistances?

Question 38

An initial voltage v(0)=0 is across a 0.1 microfarad capacitor. The current is given by the square wave in Figure 3.7, which is +1 mA for 2 ms, then -1 mA for 2 ms, and so on. What is the voltage at t=2 ms?

Question 39

Relative to mica, which has a relative dielectric constant of 7.0, how much larger is the capacitance of a parallel-plate capacitor if the dielectric is replaced with water, which has a relative dielectric constant of 78.5?

Question 40

A 2 H inductor is connected to a 10 V DC source via a switch that closes at t=0. The initial current is zero. What is the current i(t) at t=1s?

Question 41

What are the units of capacitance, and to what other units are they equivalent?

Question 42

When combining inductors, what is the rule for a parallel combination, and how does it compare to the rule for resistors?

Question 43

What is the stored energy w(t) in a 10 microfarad capacitor when the voltage across it, v(t), is given by the waveform in Figure 3.6(a), specifically at t=1s when the voltage is 1000V?

Question 44

For the Linear Variable Differential Transformer (LVDT) described in Section 3.7, what is the output voltage vo(t) when the iron core is centered in the coils?

Question 45

What is a 'parasitic element' in the context of a real capacitor or inductor?

Question 46

A constant voltage of 12 V is applied to a 0.1 microfarad capacitor. What is the current flowing through the capacitor?

Question 47

The voltage across a 0.1 microfarad capacitor is v(t) = 500[1 - cos(10^4 t)] V. What is the initial charge q(0) on the capacitor?

Question 48

What is the alternative expression for stored energy in a capacitor, w(t), in terms of charge q(t) and capacitance C?

Question 49

In the fluid-flow analogy, a capacitor is represented as a reservoir with an elastic membrane. What physical quantity in the capacitor is analogous to the displaced fluid volume starting from the unstretched membrane position?

Question 50

A circuit contains two inductors in series, L1 and L2. How is their equivalent inductance, Leq, determined?