Question 1

What is the battery current Ibat when the switch in the figure is closed?

Accepted Answer

A) 8.0 A 
B) 9.14 A 
C) 1.09 A 
D) 12.5 A 
A) 8.0 A 
B) 9.14 A 
C) 1.09 A 
D) 12.5 A

Question 2

The emf (electromotive force)is an

Accepted Answer

A) electric force vector. 
B) electric force magnitude. 
C) electric field vector. 
D) electric field magnitude. 
E) None are correct. 
A) electric force vector. 
B) electric force magnitude. 
C) electric field vector. 
D) electric field magnitude. 
E) None are correct.

Question 3

A copper wire has a diameter of dCu = 0.0400 cm,is 3.00 m long,has a resistivity of 1.72 * 10-8 $\varOmega$m and has a carrier density of 8.50 * 1028 electrons/m3.The copper wire is attached to an equal length of aluminum wire with a a carrier density of 6.02 * 1028 electrons/m3.A current of 0.400 A flows through the copper and aluminum wires.If the ratio of the current densities the two wires,JCu/JAl is 0.50,what is the diameter of the aluminum wire?

Accepted Answer

A) 0.0800 cm 
B) 0.0283 cm 
C) 0.0200 cm 
D) 0.0565 cm 
E) 0.0400 cm 
A) 0.0800 cm 
B) 0.0283 cm 
C) 0.0200 cm 
D) 0.0565 cm 
E) 0.0400 cm

Question 4

Two identical light bulbs are connected to a battery.Will the light bulbs be brighter if they are connected to the battery in series or in parallel?

Accepted Answer

A) in series 
B) in parallel 
C) The brightness will be the same in series and in parallel. 
D) There is not enough information to determine an answer. 
A) in series 
B) in parallel 
C) The brightness will be the same in series and in parallel. 
D) There is not enough information to determine an answer.

Question 5

What is voltage across the 8 $\varOmega$resistor?

Accepted Answer

A) 4 V 
B) 8 V 
C) 12 V 
D) 1/4 V 
E) 1/8 V 
A) 4 V 
B) 8 V 
C) 12 V 
D) 1/4 V 
E) 1/8 V

Question 6

Which one of these circuits has the highest resistance between points A and B?

Accepted Answer

A) The left one has the highest resistance. 
B) The middle one has the highest resistance. 
C) The right one has the highest resistance. 
D) All three have the same resistance. 
E) The middle and right ones have the same resistance,and the left one's is lower. 
A) The left one has the highest resistance. 
B) The middle one has the highest resistance. 
C) The right one has the highest resistance. 
D) All three have the same resistance. 
E) The middle and right ones have the same resistance,and the left one's is lower.

Question 7

A certain brand of hot dog cooker applies a potential difference of 120 V to opposite ends of the hot dogs and cooks by means of the joule heat produced.If energy of 62 kJ is needed to cook each hot dog,what current is needed to cook four hot dogs simultaneously in 1.5 min? Assume a parallel connection.

Accepted Answer

A) 2.5 A 
B) 5.1 A 
C) 10 A 
D) 15 A 
E) 23 A 
A) 2.5 A 
B) 5.1 A 
C) 10 A 
D) 15 A 
E) 23 A

Question 8

When two resistors are connected in series across a 12-V battery,1.1A flows.When they are connected in parallel across the same battery,6.3A flows.What is the smaller resistor's value?

Accepted Answer

A) 2.5 $\varOmega$ 
B) 8.4 $\varOmega$ 
C) 1.7 $\varOmega$ 
D) 0.55$\varOmega$ 
A) 2.5 $\varOmega$ 
B) 8.4 $\varOmega$ 
C) 1.7 $\varOmega$ 
D) 0.55$\varOmega$

Question 9

What is the current in the 5 $\varOmega$ resistor?

Accepted Answer

A) 3.3 A 
B) 2.2 A 
C) 330 A 
D) 6.6 A 
E) 165 A 
A) 3.3 A 
B) 2.2 A 
C) 330 A 
D) 6.6 A 
E) 165 A

Question 10

Suppose,while cooling your bedroom 0.25 moles of electrons pass through your air conditioner each hour.What current does your air conditioner draw when it is running?

Accepted Answer

A) 6.7 A 
B) 25 A 
C) 15 A 
D) 8.3 A 
E) 5.5 A 
A) 6.7 A 
B) 25 A 
C) 15 A 
D) 8.3 A 
E) 5.5 A

Question 11

Two identical bulbs,A and B,are connected in an electrical circuit as shown in the figure.R is the resistance connected in series with the each bulb.Initially they are glowing with equal intensity.Bulb A is removed from the socket;the potential difference across the empty socket A will

Accepted Answer

A) decrease. 
B) increase. 
C) not change. 
D) become zero. 
A) decrease. 
B) increase. 
C) not change. 
D) become zero.

Question 12

A circuit containing a battery with V = 10.3 V and a resistor R1 = 15.7 $\varOmega$ is shown.If we replace the wire between points a and b with a second resistor R2 = 26.8 $\varOmega$,by how much (in a)will the total current through the battery change?

Accepted Answer

A) -0.265 
B) -0.331 
C) -0.414 
D) -0.517 
E) -0.646 
A) -0.265 
B) -0.331 
C) -0.414 
D) -0.517 
E) -0.646

Question 13

Which of the following has the smallest current flowing through it?

Accepted Answer

A) a 1-m long copper wire of diameter 1 mm connected to a battery of 10 V 
B) a 0.5-m long copper wire of diameter 0.5 mm connected to a 5-V battery 
C) a 2-m long copper wire of diameter 2 mm connected to a 20-V battery 
D) a 1-m long copper wire of diameter 0.5 mm connected to a 5-V battery 
E) All of the choices have the same current. 
A) a 1-m long copper wire of diameter 1 mm connected to a battery of 10 V 
B) a 0.5-m long copper wire of diameter 0.5 mm connected to a 5-V battery 
C) a 2-m long copper wire of diameter 2 mm connected to a 20-V battery 
D) a 1-m long copper wire of diameter 0.5 mm connected to a 5-V battery 
E) All of the choices have the same current.

Question 14

A current flows through an aluminum wire.The aluminum wire has a length of 2.00 m,a diameter of 0.0300 cm,and a carrier density of 6.02 * 1028 electrons/m3.If the electron drift velocity is 1.84 * 10-4 m/s,what is the current in the wire?

Accepted Answer

A) 0.500 A 
B) 0.125 A 
C) 0.313 A 
D) 0.102 A 
E) 0.230 A 
A) 0.500 A 
B) 0.125 A 
C) 0.313 A 
D) 0.102 A 
E) 0.230 A

Question 15

Two conductors are made from the same material and are of the same length but one has a circular cross sectional area with diameter 1.2 mm and the other is square with 0.6 mm on each side.What is the ratio Rcircular/Rsquare of their resistances?

Accepted Answer

A) Rcircular/Rsquare = 2 
B) Rcircular/Rsquare = 1/$\pi$ 
C) Rcircular/Rsquare = $\pi$/2 
D) Rcircular/Rsquare = 4 
E) Rcircular/Rsquare = 1/2 
A) Rcircular/Rsquare = 2 
B) Rcircular/Rsquare = 1/$\pi$ 
C) Rcircular/Rsquare = $\pi$/2 
D) Rcircular/Rsquare = 4 
E) Rcircular/Rsquare = 1/2

Question 16

In circuit shown,three identical light bulbs are connected.Initially switch S is closed.When switch S is opened,bulb 3 turns off.As for bulbs 1 and 2,which statement is true?

Accepted Answer

A) Bulb 1 gets brighter while bulb 2 gets dimmer. 
B) Both bulbs 1 and 2 get brighter. 
C) Both bulbs 1 and 2 get dimmer. 
D) Bulb 1 gets dimmer while bulb 2 gets brighter. 
A) Bulb 1 gets brighter while bulb 2 gets dimmer. 
B) Both bulbs 1 and 2 get brighter. 
C) Both bulbs 1 and 2 get dimmer. 
D) Bulb 1 gets dimmer while bulb 2 gets brighter.

Question 17

A particular wire has a diameter of 1.7 mm and length of 1.3 m.If the resistivity of the metal from which the wire is made is 2.0 * 10-8 $\varOmega$ m,and 45 $\mu$V is the observed potential drop measured across the wire,what current is flowing in the wire?

Accepted Answer

A) 3.9 mA 
B) 6.6 mA 
C) 16 mA 
D) 26 mA 
A) 3.9 mA 
B) 6.6 mA 
C) 16 mA 
D) 26 mA

Question 18

What is the current in the 20 $\varOmega$resistor in the circuit in the figure?

Accepted Answer

A) 0.33 A 
B) 0.60 A 
C) 1.0 A 
D) 1.5 A 
E) 3.0 A 
A) 0.33 A 
B) 0.60 A 
C) 1.0 A 
D) 1.5 A 
E) 3.0 A

Question 19

Assuming that there are 0.845 * 1029 electrons per m3 in a wire of with cross sectional area 69 mm2 and carrying a current of 30 mA,what is the drift velocity?

Accepted Answer

A) 3.21 * 10-8 m/s 
B) 2.52 * 10-5 m/s 
C) 8.22 * 10-3 m/s 
D) 4.12 * 106 m/s 
E) 3.00 * 108 m/s 
A) 3.21 * 10-8 m/s 
B) 2.52 * 10-5 m/s 
C) 8.22 * 10-3 m/s 
D) 4.12 * 106 m/s 
E) 3.00 * 108 m/s

Question 20

Suppose your air conditioner draws 5.5A while cooling your bedroom.How many moles of electrons pass through the air conditioner each hour the AC is on?

Accepted Answer

A) 0.25 
B) 2.0 
C) 0.024 
D) 0.21 
E) 2.4 * 10-7 
A) 0.25 
B) 2.0 
C) 0.024 
D) 0.21 
E) 2.4 * 10-7

Exam 25: Current and Resistance

What is the battery current Ibat when the switch in the figure is closed?

The emf (electromotive force)is an

Two identical light bulbs are connected to a battery.Will the light bulbs be brighter if they are connected to the battery in series or in parallel?

What is voltage across the 8 Ω\varOmegaΩ resistor?

Which one of these circuits has the highest resistance between points A and B?

When two resistors are connected in series across a 12-V battery,1.1A flows.When they are connected in parallel across the same battery,6.3A flows.What is the smaller resistor's value?

What is the current in the 5 Ω\varOmegaΩ resistor?

Suppose,while cooling your bedroom 0.25 moles of electrons pass through your air conditioner each hour.What current does your air conditioner draw when it is running?

Two identical bulbs,A and B,are connected in an electrical circuit as shown in the figure.R is the resistance connected in series with the each bulb.Initially they are glowing with equal intensity.Bulb A is removed from the socket;the potential difference across the empty socket A will

A circuit containing a battery with V = 10.3 V and a resistor R1 = 15.7 Ω\varOmegaΩ is shown.If we replace the wire between points a and b with a second resistor R2 = 26.8 Ω\varOmegaΩ ,by how much (in a)will the total current through the battery change?

Which of the following has the smallest current flowing through it?

A current flows through an aluminum wire.The aluminum wire has a length of 2.00 m,a diameter of 0.0300 cm,and a carrier density of 6.02 * 1028 electrons/m3.If the electron drift velocity is 1.84 * 10-4 m/s,what is the current in the wire?

Two conductors are made from the same material and are of the same length but one has a circular cross sectional area with diameter 1.2 mm and the other is square with 0.6 mm on each side.What is the ratio Rcircular/Rsquare of their resistances?

In circuit shown,three identical light bulbs are connected.Initially switch S is closed.When switch S is opened,bulb 3 turns off.As for bulbs 1 and 2,which statement is true?

A particular wire has a diameter of 1.7 mm and length of 1.3 m.If the resistivity of the metal from which the wire is made is 2.0 * 10-8 Ω\varOmegaΩ m,and 45 μ\muμ V is the observed potential drop measured across the wire,what current is flowing in the wire?

What is the current in the 20 Ω\varOmegaΩ resistor in the circuit in the figure?

Assuming that there are 0.845 * 1029 electrons per m3 in a wire of with cross sectional area 69 mm2 and carrying a current of 30 mA,what is the drift velocity?

Suppose your air conditioner draws 5.5A while cooling your bedroom.How many moles of electrons pass through the air conditioner each hour the AC is on?

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Filters

What is the battery current I_bat when the switch in the figure is closed?

What is voltage across the 8 $\varOmega$ resistor? $What is voltage across the 8 \varOmega resistor?$

What is the current in the 5 $\varOmega$ resistor? $What is the current in the 5 \varOmega resistor?$

A current flows through an aluminum wire.The aluminum wire has a length of 2.00 m,a diameter of 0.0300 cm,and a carrier density of 6.02 * 10²⁸ electrons/m³.If the electron drift velocity is 1.84 * 10^-4 m/s,what is the current in the wire?

Two conductors are made from the same material and are of the same length but one has a circular cross sectional area with diameter 1.2 mm and the other is square with 0.6 mm on each side.What is the ratio R_circular/R_square of their resistances?

A particular wire has a diameter of 1.7 mm and length of 1.3 m.If the resistivity of the metal from which the wire is made is 2.0 * 10^-8 $\varOmega$ m,and 45 $\mu$ V is the observed potential drop measured across the wire,what current is flowing in the wire?

What is the current in the 20 $\varOmega$ resistor in the circuit in the figure? $What is the current in the 20 \varOmega resistor in the circuit in the figure?$

Assuming that there are 0.845 * 10²⁹ electrons per m³ in a wire of with cross sectional area 69 mm² and carrying a current of 30 mA,what is the drift velocity?