Question 1

The circuit below contains 4 100-W light bulbs.The emf is 110 V.Which light bulb(s)is(are)brightest?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) C and D 
A) A 
B) B 
C) C 
D) D 
E) C and D

Question 2

What is the potential difference VB - VA when I = 0.50 A in the circuit segment shown below?

Accepted Answer

A) +28 V 
B) +2.0 V 
C) -28 V 
D) -2.0 V 
E) +18 V 
A) +28 V 
B) +2.0 V 
C) -28 V 
D) -2.0 V 
E) +18 V

Question 3

What is the resistance of a wire made of a material with a resistivity of 3.2*10 - 8 $\Omega$ . m if its length is 2.5 m and its diameter is 0.50 mm?

Accepted Answer

A) 0.16 $\Omega$ 
B) 0.10 $\Omega$ 
C) 1.28 $\Omega$ 
D) 0.41 $\Omega$ 
E) 0.81 $\Omega$ 
A) 0.16 $\Omega$ 
B) 0.10 $\Omega$ 
C) 1.28 $\Omega$ 
D) 0.41 $\Omega$ 
E) 0.81 $\Omega$

Question 4

How many time constants must elapse if an initially charged capacitor is to discharge 55% of its stored energy through a resistor?

Accepted Answer

A) 0.60 
B) 0.46 
C) 0.52 
D) 0.40 
E) 1.1 
A) 0.60 
B) 0.46 
C) 0.52 
D) 0.40 
E) 1.1

Question 5

At what rate is thermal energy being generated in the 2R-resistor when $\varepsilon$ = 12 V and R = 3.0  $\Omega$?

Accepted Answer

A) 12 W 
B) 24 W 
C) 6.0 W 
D) 3.0 W 
E) 1.5 W 
A) 12 W 
B) 24 W 
C) 6.0 W 
D) 3.0 W 
E) 1.5 W

Question 6

A nichrome wire and an aluminum wire,each with the same initial resistance,have the same change in resistance when heated separately.($\rho$Al = 2.82 *10 - 8 $\Omega$.m;$\alpha$Al = 3.9 *10 - 3 /  $\degree$C;$\rho$nichrome = 1.50* 10 - 6 $\Omega$.m;$\alpha$nichrome = 0.40 * 10 - 3 /  $\degree$C. )The ratio of the temperature change of the nichrome wire to the temperature change of the aluminum wire is

Accepted Answer

A) 0.019. 
B) 0.10. 
C) 0.18. 
D) 9.8. 
E) 53. 
A) 0.019. 
B) 0.10. 
C) 0.18. 
D) 9.8. 
E) 53.

Question 7

A 10-V battery is connected to a 15- $\Omega$ resistor and an unknown resistor R,as shown.The current in the circuit is 0.40 A.How much heat is produced in the 15- $\Omega$resistor in 2.0 min?

Accepted Answer

A) 0.40 kJ 
B) 0.19 kJ 
C) 0.29 kJ 
D) 0.72 kJ 
E) 0.80 kJ 
A) 0.40 kJ 
B) 0.19 kJ 
C) 0.29 kJ 
D) 0.72 kJ 
E) 0.80 kJ

Question 8

If the current in the 4.0-$\Omega$resistor is 1.4 A,what is the magnitude of the potential difference,VA - VB?

Accepted Answer

A) 69 V 
B) 55 V 
C) 62 V 
D) 48 V 
E) 31 V 
A) 69 V 
B) 55 V 
C) 62 V 
D) 48 V 
E) 31 V

Question 9

If R = 3.0 k$\Omega$,C = 5.0 mF,$\varepsilon$ = 6.0 V,Q = 15 mC,and I = 4.0 mA,what is the potential difference Vb - Va?

Accepted Answer

A) -3.0 V 
B) +9.0 V 
C) -15 V 
D) +21 V 
E) -6.0 V 
A) -3.0 V 
B) +9.0 V 
C) -15 V 
D) +21 V 
E) -6.0 V

Question 10

The circuit below contains 5 identical light bulbs.The emf is 110 V.Which light bulb(s)is(are)brightest?

Accepted Answer

A) A: The one closest to the positive terminal of the battery. 
B) A and C: The bulbs closest to the positive terminal of the battery. 
C) A and B: Because they are closest to the terminals of the battery. 
D) C and D: Because they receive current from A and B and from E. 
E) E: Because the potential difference across E is that of the battery. 
A) A: The one closest to the positive terminal of the battery. 
B) A and C: The bulbs closest to the positive terminal of the battery. 
C) A and B: Because they are closest to the terminals of the battery. 
D) C and D: Because they receive current from A and B and from E. 
E) E: Because the potential difference across E is that of the battery.

Question 11

The algebraic sum of the changes of potential around any closed circuit loop is

Accepted Answer

A) zero. 
B) maximum. 
C) zero only if there are no sources of emf in the loop. 
D) maximum if there are no sources of emf in the loop. 
E) equal to the sum of the currents in the branches of the loop. 
A) zero. 
B) maximum. 
C) zero only if there are no sources of emf in the loop. 
D) maximum if there are no sources of emf in the loop. 
E) equal to the sum of the currents in the branches of the loop.

Question 12

A rod (length = 80 cm)with a rectangular cross section (1.5 mm * 2.0 mm)has a resistance of 0.20 $\Omega$.What is the resistivity of the material used to make the rod?

Accepted Answer

A) 6.0 *10 - 7 $\Omega$ . m 
B) 3.8 *10 - 7 $\Omega$ . m 
C) 7.5 *10F1F1F1S1- 7 $\Omega$ .m 
D) 3.0 *10 - 7 $\Omega$ . m 
E) 4.8 *10 - 7 $\Omega$ .m 
A) 6.0 *10 - 7 $\Omega$ . m 
B) 3.8 *10 - 7 $\Omega$ . m 
C) 7.5 *10F1F1F1S1- 7 $\Omega$ .m 
D) 3.0 *10 - 7 $\Omega$ . m 
E) 4.8 *10 - 7 $\Omega$ .m

Question 13

The temperature coefficient of resistivity of iron is 5.0 *10 - 3 / $\degree$C;that of carbon is-0.50 *10 - 3 / $\degree$C.When an iron wire and a carbon rod,each having the same 10 $\Omega$ resistance at 20$\degree$C,are cooled from that temperature to -80$\degree$C,the new ratio of the resistance of the carbon rod to the resistance of the iron wire at the lower temperature is

Accepted Answer

A) -0.10. 
B) +1.9. 
C) +2.1. 
D) -10. 
E) +10. 
A) -0.10. 
B) +1.9. 
C) +2.1. 
D) -10. 
E) +10.

Question 14

At t = 0 the switch S is closed with the capacitor uncharged.If C = 30 $\mu$F,$\varepsilon$ = 50 V,and R = 10 k$\Omega$,what is the potential difference across the capacitor when I = 2.0 mA?

Accepted Answer

A) 20 V 
B) 15 V 
C) 25 V 
D) 30 V 
E) 45 V 
A) 20 V 
B) 15 V 
C) 25 V 
D) 30 V 
E) 45 V

Question 15

A circuit consists of N resistors,all of resistance R,connected as shown below.A potential difference V is applied to the circuit.The equivalent resistance of the circuit is

Accepted Answer

A)  $$\frac { R } { 4 }$$ . 
B) R. 
C)  $$\frac { N R } { 4 }$$ . 
D) NR. 
E) 4NR. 
A)  $$\frac { R } { 4 }$$ . 
B) R. 
C)  $$\frac { N R } { 4 }$$ . 
D) NR. 
E) 4NR.

Question 16

If R = 2.0 k$\Omega$,C = 4.0 mF,$\varepsilon$ = 8.0 V,Q = 20 mC,and I = 3.0 mA,what is the potential difference Vb - Va?

Accepted Answer

A) +7.0 V 
B) +19 V 
C) +9.0 V 
D) -3.0 V 
E) -14 V 
A) +7.0 V 
B) +19 V 
C) +9.0 V 
D) -3.0 V 
E) -14 V

Question 17

The circuit below contains three 100-watt light bulbs.The emf $\varepsilon$ = 110 V.Which light bulb(s)is(are)the brightest?

Accepted Answer

A) A 
B) B 
C) C 
D) B and C 
E) All three are equally bright. 
A) A 
B) B 
C) C 
D) B and C 
E) All three are equally bright.

Question 18

A small bulb is rated at 7.50 W when operated at 125 V.The tungsten filament has a temperature coefficient of resistivity $\alpha$ = 4.50*10 - 3 /  $\degree$C.When the filament is hot and glowing,its temperature is seven times room temperature (20  $\degree$C).What is the resistance of the filament (in ohms)at room temperature?

Accepted Answer

A) 234 
B) 1 350 
C) 2 080 
D) 4 530 
E) 5 630 
A) 234 
B) 1 350 
C) 2 080 
D) 4 530 
E) 5 630

Question 19

What is the resistance of 1 000 m of 4-mm diameter copper wire?
($\rho$Cu = 1.7 * 10-8$\Omega$ .m)

Accepted Answer

The answer of What is the resistance of 1 000...

Question 20

In the Drude model of electrical conduction,the current density is NOT directly proportional to

Accepted Answer

A) the average time interval between successive collisions. 
B) the number of charge carriers per unit volume. 
C) the square of the electron charge. 
D) the electric field present in the wire. 
E) the resistivity of the wire. 
A) the average time interval between successive collisions. 
B) the number of charge carriers per unit volume. 
C) the square of the electron charge. 
D) the electric field present in the wire. 
E) the resistivity of the wire.

Exam 21: Current and Direct Current Circuits

The circuit below contains 4 100-W light bulbs.The emf is 110 V.Which light bulb(s)is(are)brightest?

What is the potential difference VB - VA when I = 0.50 A in the circuit segment shown below?

What is the resistance of a wire made of a material with a resistivity of 3.2*10 - 8 Ω\OmegaΩ . m if its length is 2.5 m and its diameter is 0.50 mm?

How many time constants must elapse if an initially charged capacitor is to discharge 55% of its stored energy through a resistor?

At what rate is thermal energy being generated in the 2R-resistor when ε\varepsilonε = 12 V and R = 3.0 Ω\OmegaΩ ?

A 10-V battery is connected to a 15- Ω\OmegaΩ resistor and an unknown resistor R,as shown.The current in the circuit is 0.40 A.How much heat is produced in the 15- Ω\OmegaΩ resistor in 2.0 min?

If the current in the 4.0- Ω\OmegaΩ resistor is 1.4 A,what is the magnitude of the potential difference,VA - VB?

If R = 3.0 k Ω\OmegaΩ ,C = 5.0 mF, ε\varepsilonε = 6.0 V,Q = 15 mC,and I = 4.0 mA,what is the potential difference Vb - Va?

The circuit below contains 5 identical light bulbs.The emf is 110 V.Which light bulb(s)is(are)brightest?

The algebraic sum of the changes of potential around any closed circuit loop is

A rod (length = 80 cm)with a rectangular cross section (1.5 mm * 2.0 mm)has a resistance of 0.20 Ω\OmegaΩ .What is the resistivity of the material used to make the rod?

At t = 0 the switch S is closed with the capacitor uncharged.If C = 30 μ\muμ F, ε\varepsilonε = 50 V,and R = 10 k Ω\OmegaΩ ,what is the potential difference across the capacitor when I = 2.0 mA?

A circuit consists of N resistors,all of resistance R,connected as shown below.A potential difference V is applied to the circuit.The equivalent resistance of the circuit is

If R = 2.0 k Ω\OmegaΩ ,C = 4.0 mF, ε\varepsilonε = 8.0 V,Q = 20 mC,and I = 3.0 mA,what is the potential difference Vb - Va?

The circuit below contains three 100-watt light bulbs.The emf ε\varepsilonε = 110 V.Which light bulb(s)is(are)the brightest?

What is the resistance of 1 000 m of 4-mm diameter copper wire? ( ρ\rhoρ Cu = 1.7 * 10-8 Ω\OmegaΩ .m)

In the Drude model of electrical conduction,the current density is NOT directly proportional to

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What is the potential difference V_B - V_Awhen I = 0.50 A in the circuit segment shown below?

What is the resistance of a wire made of a material with a resistivity of 3.2*10 ^- ⁸ $\Omega$ . m if its length is 2.5 m and its diameter is 0.50 mm?

At what rate is thermal energy being generated in the 2R-resistor when $\varepsilon$ = 12 V and R = 3.0 $\Omega$ ? $At what rate is thermal energy being generated in the 2R-resistor when \varepsilon = 12 V and R = 3.0 \Omega ?$

If the current in the 4.0- $\Omega$ resistor is 1.4 A,what is the magnitude of the potential difference,V_A - V_B? $If the current in the 4.0- \Omega resistor is 1.4 A,what is the magnitude of the potential difference,V<sub>A</sub> - V<sub>B</sub>?$

If R = 3.0 k $\Omega$ ,C = 5.0 mF, $\varepsilon$ = 6.0 V,Q = 15 mC,and I = 4.0 mA,what is the potential difference V_b - V_a? $If R = 3.0 k \Omega ,C = 5.0 mF, \varepsilon = 6.0 V,Q = 15 mC,and I = 4.0 mA,what is the potential difference V<sub>b</sub> - V<sub>a</sub>?$

A rod (length = 80 cm)with a rectangular cross section (1.5 mm * 2.0 mm)has a resistance of 0.20 $\Omega$ .What is the resistivity of the material used to make the rod?

If R = 2.0 k $\Omega$ ,C = 4.0 mF, $\varepsilon$ = 8.0 V,Q = 20 mC,and I = 3.0 mA,what is the potential difference V_b - V_a? $If R = 2.0 k \Omega ,C = 4.0 mF, \varepsilon = 8.0 V,Q = 20 mC,and I = 3.0 mA,what is the potential difference V<sub>b</sub> - V<sub>a</sub>?$

The circuit below contains three 100-watt light bulbs.The emf $\varepsilon$ = 110 V.Which light bulb(s)is(are)the brightest? $The circuit below contains three 100-watt light bulbs.The emf \varepsilon = 110 V.Which light bulb(s)is(are)the brightest?$

What is the resistance of 1 000 m of 4-mm diameter copper wire? ( $\rho$ _Cu = 1.7 * 10^-8 $\Omega$ .m)