CHAPTER 4 - Direct-Current Circuit Basics GIBILISCO 7TH EDITION

A

We have an unlimited supply of 33-Ω resistors, each one capable of dissipating 0.50 W.

We want a 33-Ω resistor that can dissipate 18 W (a figure that includes a 2-W safety margin).

We can get that component by wiring up

(a) a 6 × 6 series-parallel matrix of individual resistors.

(b) a 9 × 4 series-parallel matrix of individual resistors.

(c) a 3 × 12 series-parallel matrix of individual resistors.

(d) Any of the above

C

We connect a 6.30-V lantern battery across a 330-Ω resistor. The resistor dissipates

(a) 19.0 mW of power.

(b) 8.31 mW of power.

(c) 120 mW of power.

(d) We need more information to calculate it.

C

If we connect 10 components in parallel, each one with a DC conductance of 0.15 S, what's

the net DC conductance of the combination?

(a) 0.015 S

(b) 0.15 S

(c) 1.5 S

(d) 15 S

B

We have an unlimited supply of 100-Ω resistors, each one capable of dissipating 1.00 W.

We want a resistance of 100 Ω capable of dissipating up to 12 W (a figure that includes a

2.5-W safety margin). Which of the following circuits is the smallest n × n matrix that will

work here?

(a) A 5 × 5 matrix

(b) A 4 × 4 matrix

(c) A 3 × 3 matrix

(d) A 2 × 2 matrix

D

If we connect a 6.3-V battery across a 330-Ω resistor, the current is

(a) 72 mA.

(b) 36 mA.

(c) 12 mA.

(d) 19 mA.

A

The voltage across a resistor is 2.2 V. The resistor dissipates 400 mW. What's its resistance?

(a) 12 Ω

(b) 24 Ω

(c) 48 Ω

(d) 96 Ω

D

If we connect eight resistors in parallel, all identical and each with a value of 1.100 k, we get

a component with a resistance of

(a) 8800 Ω.

(b) 4840 Ω.

(c) 1100 Ω.

(d) 137.5 Ω.

B

We wire up three resistors in parallel: 600 Ω, 300 Ω, and 200 Ω. Then we connect

a 12-V battery across the combination. How much current does the 300-Ω resistor draw all by

itself?

(a) 80 mA

(b) 40 mA

(c) 33 mA

(d) 11 mA

A

If we decrease the conductance of a resistor by a factor of 16 while leaving it connected to a

source of constant DC voltage, then the power that the resistor dissipates will

(a) decrease by a factor of 16.

(b) decrease by a factor of 4.

(c) increase by a factor of 4.

(d) increase by a factor of 16.

C

If we double the DC voltage across a resistor and double its resistance as well, then the power

that the resistor dissipates will

(a) get cut in half.

(b) stay the same.

(c) double.

(d) quadruple.

B

If we double the DC voltage across a resistor and double its resistance as well, then the

current that the resistor draws will

(a) get cut in half.

(b) stay the same.

(c) double.

(d) quadruple.

D

If we know the current through a component (in amperes) and its resistance (in Ω), how

can we calculate the energy (in joules) that the component consumes?

(a) Square the current and then multiply by the resistance.

(b) Multiply the current by the resistance.

(c) Divide the resistance by the current.

(d) We need more information to do it.

C

Suppose that 33.300 mA DC flows through a resistance of 3.333333 k. How can we best

express the voltage across this resistance, taking significant figures into account?

(a) 111 V

(b) 111.0 V

(c) 111.00 V

(d) 110.999 V

A

If a potentiometer carries 18.5 mA DC and we set its resistance to 1.12 k, how much power

does it dissipate?

(a) 383 mW

(b) 20.7 mW

(c) 60.5 mW

(d) 67.8 mW

B

We wire up seven 70.0-Ω resistors in parallel, and then connect a 12.6-V battery across the

whole combination. How much current gets drawn from the battery?

(a) 25.7 mA

(b) 1.26 A

(c) 794 mA

(d) 180 mA

C

We remove three of the resistors from the circuit in Question 15. What will happen to the

current drawn by any one of the remaining four resistors?

(a) It will go down to zero.

(b) It will become 4/7 of its previous value.

(c) It will stay the same.

(d) It will become 7/4 of its previous value.

D

We connect resistors with values of 180, 270, and 680 Ω in series with a 12.6-V battery.

How much power does the set of resistors dissipate as a whole?

(a) 7.12 W

(b) 89.7 W

(c) 11.2 mW

(d) 140 mW

A

The three primary units that engineers use when working with DC systems are the

(a) ampere, volt, and ohm.

(b) watt, joule, and volt.

(c) siemens, ampere, and joule.

(d) erg, joule, and ohm.

B

A direct current of 3.00 A flows through a component whose conductance is 0.250 S. What's

the voltage across the component?

(a) 0.750 V

(b) 12.0 V

(c) 36.0 V

(d) We need more information to calculate it.

C

A direct current of 3.00 A flows through a component whose conductance is 0.250 S. How

much power does the component dissipate?

(a) 750 mW

(b) 2.25 W

(c) 36.0 W

(d) We need more information to calculate it.