Question 1

Consider two copper wires with circular cross-sections and equal lengths. One wire has 3 times the diameter of the other. How do the resistances of these two wires compare?

Accepted Answer

A)  The thicker wire has $1 / 3$ the resistance of the thinner wire. 
B)  The thicker wire has 9 times the resistance of the thinner wire. 
C)  The thicker wire has 3 times the resistance of the thinner wire. 
D)  The thicker wire has $1 / 9$ the resistance of the thinner wire. 
E)  The thicker wire has $\sqrt { 3 }$ times the resistance of the thinner wire. 
A)  The thicker wire has $1 / 3$ the resistance of the thinner wire. 
B)  The thicker wire has 9 times the resistance of the thinner wire. 
C)  The thicker wire has 3 times the resistance of the thinner wire. 
D)  The thicker wire has $1 / 9$ the resistance of the thinner wire. 
E)  The thicker wire has $\sqrt { 3 }$ times the resistance of the thinner wire.

Question 2

What potential difference is required to cause $4.00$ A to flow through a resistance of $330 \Omega$ ?

Accepted Answer

A)  $1320 \mathrm {~V}$ 
B)  $334 \mathrm {~V}$ 
C)  $12.1 \mathrm {~V}$ 
D)  $82.5 \mathrm {~V}$ 
A)  $1320 \mathrm {~V}$ 
B)  $334 \mathrm {~V}$ 
C)  $12.1 \mathrm {~V}$ 
D)  $82.5 \mathrm {~V}$

Question 3

A light bulb operating at a dc voltage of $120 \mathrm {~V}$ has a power rating of $60 \mathrm {~W}$. How much current is flowing through this bulb?

Accepted Answer

A)  $1.5 \mathrm {~A}$ 
B)  $2.5 \mathrm {~A}$ 
C)  $1.0 \mathrm {~A}$ 
D)  $0.50 \mathrm {~A}$ 
E)  $2.0 \mathrm {~A}$ 
A)  $1.5 \mathrm {~A}$ 
B)  $2.5 \mathrm {~A}$ 
C)  $1.0 \mathrm {~A}$ 
D)  $0.50 \mathrm {~A}$ 
E)  $2.0 \mathrm {~A}$

Question 4

A $120 - \Omega$ laboratory resistor is rated at $0.25 \mathrm {~W}$. How much current can safely flow through the resistor?

Accepted Answer

A)  $22 \mathrm {~mA}$ 
B)  $30 \mathrm {~A}$ 
C)  $46 \mathrm {~mA}$ 
D)  $2.1 \mathrm {~mA}$ 
A)  $22 \mathrm {~mA}$ 
B)  $30 \mathrm {~A}$ 
C)  $46 \mathrm {~mA}$ 
D)  $2.1 \mathrm {~mA}$

Question 5

A flashlight draws $0.133$ A from a $3.0$ - $V$ battery pack. In $2.0$ minutes (a) how much charge flows from the battery, (b) how much energy does the battery supply, and (c) how many electrons have passed any point in the circuit every second?

Accepted Answer

The answer of A flashlight draws $0.133$ A from a...

Question 6

The voltage drop across a metal bar is $5.0 \mathrm {~V}$ while a current of $10.0 \mathrm {~mA}$ flows through it. How much power does this bar dissipate?

Accepted Answer

A)  $0.50 \mathrm {~kW}$ 
B)  $500 \mu \mathrm { W }$ 
C)  $2.5 \mathrm {~kW}$ 
D)  $50 \mathrm {~mW}$ 
A)  $0.50 \mathrm {~kW}$ 
B)  $500 \mu \mathrm { W }$ 
C)  $2.5 \mathrm {~kW}$ 
D)  $50 \mathrm {~mW}$

Question 7

A current of $5.0$ A flows through an electrical device for 10 seconds. How many electrons flow through this device during this time? $\left( e = 1.60 \times 10 ^ { - 19 } \mathrm { C } \right)$

Accepted Answer

A)  20 
B)  $0.20$ 
C)  $31 \times 10 ^ { 20 }$ 
D)  $3.1 \times 10 ^ { 20 }$ 
E)  $2.0$ 
A)  20 
B)  $0.20$ 
C)  $31 \times 10 ^ { 20 }$ 
D)  $3.1 \times 10 ^ { 20 }$ 
E)  $2.0$

Question 8

When a 14.0-A current flows through an 8.00-Ω device for 24.0 hours, how much does this cost if energy costs $0.0900 per kW · h?

Accepted Answer

A)  $\$ 0.24$ 
B)  $\$ 2.16$ 
C)  $\$ 3.39$ 
D)  $\$ 1.04$ 
A)  $\$ 0.24$ 
B)  $\$ 2.16$ 
C)  $\$ 3.39$ 
D)  $\$ 1.04$

Question 9

A $1.0 - \mathrm { mm }$ diameter extension cord is made of metal having a resistivity of $1.68 \times 10 ^ { - 8 } \Omega \cdot \mathrm { m }$. When it carries a current of $15 \mathrm {~A}$, what is the potential difference between two points in the cord that are $100 \mathrm {~m}$ apart?

Accepted Answer

A)  $41 \mathrm {~V}$ 
B)  $32 \mathrm {~V}$ 
C)  $23 \mathrm {~V}$ 
D)  $12 \mathrm {~V}$ 
A)  $41 \mathrm {~V}$ 
B)  $32 \mathrm {~V}$ 
C)  $23 \mathrm {~V}$ 
D)  $12 \mathrm {~V}$

Question 10

If $3.0 \times 10^{15}$ electrons flow through a section of a wire of diameter $2.0 \mathrm {~mm}$ in $4.0 \mathrm {~s}$, what is the current in the wire? $\left( e = 1.60 \times 10 ^ { - 19 } \mathrm { C } \right)$

Accepted Answer

A)  $7.5 \times 10 ^ { 14 } \mathrm {~A}$ 
B)  $0.12 \mathrm {~mA}$ 
C)  $0.24 \mathrm {~mA}$ 
D)  $7.5 \times 10 ^ { 7 } \mathrm {~A}$ 
A)  $7.5 \times 10 ^ { 14 } \mathrm {~A}$ 
B)  $0.12 \mathrm {~mA}$ 
C)  $0.24 \mathrm {~mA}$ 
D)  $7.5 \times 10 ^ { 7 } \mathrm {~A}$

Question 11

The resistance of a $100 - \mathrm { cm }$ wire of cross sectional area $2 \times 10 ^ { - 6 } \mathrm {~m} ^ { 2 }$ is $400 \Omega$. What is the resistivity of the material from which this wire is made?

Accepted Answer

A)  $0.80 \times 10 ^ { - 5 } \Omega \cdot \mathrm { m }$ 
B)  $0.80 \times 10 ^ { - 6 } \Omega \cdot \mathrm { m }$ 
C)  $8.0 \times 10 ^ { - 4 } \Omega \cdot \mathrm { m }$ 
D)  $8.0 \times 10 ^ { - 6 } \Omega \mathrm { V }$ 
E)  $0.80 \times 10 ^ { - 4 } \Omega \cdot \mathrm { m }$ 
A)  $0.80 \times 10 ^ { - 5 } \Omega \cdot \mathrm { m }$ 
B)  $0.80 \times 10 ^ { - 6 } \Omega \cdot \mathrm { m }$ 
C)  $8.0 \times 10 ^ { - 4 } \Omega \cdot \mathrm { m }$ 
D)  $8.0 \times 10 ^ { - 6 } \Omega \mathrm { V }$ 
E)  $0.80 \times 10 ^ { - 4 } \Omega \cdot \mathrm { m }$

Question 12

A charge of $12 \mathrm { C }$ passes through an electroplating apparatus in $2.0 \mathrm {~min}$. What is the average current in the apparatus?

Accepted Answer

A)  $6.0 \mathrm {~A}$ 
B)  $0.10 \mathrm {~A}$ 
C)  $0.60 \mathrm {~A}$ 
D)  $1.0 \mathrm {~A}$ 
A)  $6.0 \mathrm {~A}$ 
B)  $0.10 \mathrm {~A}$ 
C)  $0.60 \mathrm {~A}$ 
D)  $1.0 \mathrm {~A}$

Question 13

For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material?

Accepted Answer

A)  power 
B)  $1 /$ (current) 
C)  resistivity 
D)  $1 /$ (resistivity) 
E)  current 
A)  power 
B)  $1 /$ (current) 
C)  resistivity 
D)  $1 /$ (resistivity) 
E)  current

Question 14

A 1500-W heater is connected to a 120-V line for 2.0 hours. How much heat energy is produced?

Accepted Answer

A)  $3.0 \mathrm {~kJ}$ 
B)  $11 \mathrm { MJ }$ 
C)  $1.5 \mathrm {~kJ}$ 
D)  $0.18 \mathrm { MJ }$ 
A)  $3.0 \mathrm {~kJ}$ 
B)  $11 \mathrm { MJ }$ 
C)  $1.5 \mathrm {~kJ}$ 
D)  $0.18 \mathrm { MJ }$

Question 15

What is the resistance of a cylindrical metal rod $1.0 \mathrm {~cm}$ in diameter and $45 \mathrm {~m}$ long, if the resistivity of the metal is $1.4 \times 10 ^ { - 8 } \Omega \cdot \mathrm { m }$ ?

Accepted Answer

A)  $0.0080 \Omega$ 
B)  $0.0063 \Omega$ 
C)  $6.3 \Omega$ 
D)  $0.80 \Omega$ 
A)  $0.0080 \Omega$ 
B)  $0.0063 \Omega$ 
C)  $6.3 \Omega$ 
D)  $0.80 \Omega$

Question 16

If a quantity you calculated has units of $\frac { \mathrm { kg } \cdot \mathrm { m } ^ { 2 } } { \mathrm {~s} \cdot \mathrm { C } ^ { 2 } }$ what is that quantity?

Accepted Answer

A)  capacitance 
B)  resistivity 
C)  potential 
D)  resistance 
E)  current 
A)  capacitance 
B)  resistivity 
C)  potential 
D)  resistance 
E)  current

Exam 18: Electric Currents

Consider two copper wires with circular cross-sections and equal lengths. One wire has 3 times the diameter of the other. How do the resistances of these two wires compare?

What potential difference is required to cause 4.004.004.00 A to flow through a resistance of 330Ω330 \Omega330Ω ?

A light bulb operating at a dc voltage of 120 V120 \mathrm {~V}120 V has a power rating of 60 W60 \mathrm {~W}60 W . How much current is flowing through this bulb?

A 120−Ω120 - \Omega120−Ω laboratory resistor is rated at 0.25 W0.25 \mathrm {~W}0.25 W . How much current can safely flow through the resistor?

A flashlight draws 0.1330.1330.133 A from a 3.03.03.0 - VVV battery pack. In 2.02.02.0 minutes (a) how much charge flows from the battery, (b) how much energy does the battery supply, and (c) how many electrons have passed any point in the circuit every second?

The voltage drop across a metal bar is 5.0 V5.0 \mathrm {~V}5.0 V while a current of 10.0 mA10.0 \mathrm {~mA}10.0 mA flows through it. How much power does this bar dissipate?

A current of 5.05.05.0 A flows through an electrical device for 10 seconds. How many electrons flow through this device during this time? (e=1.60×10−19C)\left( e = 1.60 \times 10 ^ { - 19 } \mathrm { C } \right)(e=1.60×10−19C)

When a 14.0-A current flows through an 8.00-Ω device for 24.0 hours, how much does this cost if energy costs $0.0900 per kW · h?

If 3.0×10153.0 \times 10^{15}3.0×1015 electrons flow through a section of a wire of diameter 2.0 mm2.0 \mathrm {~mm}2.0 mm in 4.0 s4.0 \mathrm {~s}4.0 s , what is the current in the wire? (e=1.60×10−19C)\left( e = 1.60 \times 10 ^ { - 19 } \mathrm { C } \right)(e=1.60×10−19C)

The resistance of a 100−cm100 - \mathrm { cm }100−cm wire of cross sectional area 2×10−6 m22 \times 10 ^ { - 6 } \mathrm {~m} ^ { 2 }2×10−6 m2 is 400Ω400 \Omega400Ω . What is the resistivity of the material from which this wire is made?

A charge of 12C12 \mathrm { C }12C passes through an electroplating apparatus in 2.0 min2.0 \mathrm {~min}2.0 min . What is the average current in the apparatus?

For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material?

A 1500-W heater is connected to a 120-V line for 2.0 hours. How much heat energy is produced?

What is the resistance of a cylindrical metal rod 1.0 cm1.0 \mathrm {~cm}1.0 cm in diameter and 45 m45 \mathrm {~m}45 m long, if the resistivity of the metal is 1.4×10−8Ω⋅m1.4 \times 10 ^ { - 8 } \Omega \cdot \mathrm { m }1.4×10−8Ω⋅m ?

If a quantity you calculated has units of kg⋅m2 s⋅C2\frac { \mathrm { kg } \cdot \mathrm { m } ^ { 2 } } { \mathrm {~s} \cdot \mathrm { C } ^ { 2 } } s⋅C2kg⋅m2​ what is that quantity?

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Filters

What potential difference is required to cause $4.00$ A to flow through a resistance of $330 \Omega$ ?

A light bulb operating at a dc voltage of $120 \mathrm {~V}$ has a power rating of $60 \mathrm {~W}$ . How much current is flowing through this bulb?

A $120 - \Omega$ laboratory resistor is rated at $0.25 \mathrm {~W}$ . How much current can safely flow through the resistor?

A flashlight draws $0.133$ A from a $3.0$ - $V$ battery pack. In $2.0$ minutes (a) how much charge flows from the battery, (b) how much energy does the battery supply, and (c) how many electrons have passed any point in the circuit every second?

The voltage drop across a metal bar is $5.0 \mathrm {~V}$ while a current of $10.0 \mathrm {~mA}$ flows through it. How much power does this bar dissipate?

A current of $5.0$ A flows through an electrical device for 10 seconds. How many electrons flow through this device during this time? $\left( e = 1.60 \times 10 ^ { - 19 } \mathrm { C } \right)$

If $3.0 \times 10^{15}$ electrons flow through a section of a wire of diameter $2.0 \mathrm {~mm}$ in $4.0 \mathrm {~s}$ , what is the current in the wire? $\left( e = 1.60 \times 10 ^ { - 19 } \mathrm { C } \right)$

The resistance of a $100 - \mathrm { cm }$ wire of cross sectional area $2 \times 10 ^ { - 6 } \mathrm {~m} ^ { 2 }$ is $400 \Omega$ . What is the resistivity of the material from which this wire is made?

A charge of $12 \mathrm { C }$ passes through an electroplating apparatus in $2.0 \mathrm {~min}$ . What is the average current in the apparatus?

What is the resistance of a cylindrical metal rod $1.0 \mathrm {~cm}$ in diameter and $45 \mathrm {~m}$ long, if the resistivity of the metal is $1.4 \times 10 ^ { - 8 } \Omega \cdot \mathrm { m }$ ?

If a quantity you calculated has units of $\frac { \mathrm { kg } \cdot \mathrm { m } ^ { 2 } } { \mathrm {~s} \cdot \mathrm { C } ^ { 2 } }$ what is that quantity?