Question 1

Consider some material that has been cooled until it has become a superconductor.If it is cooled even further its resistance will:

Accepted Answer

A) increase. 
B) decrease. 
C) stay constant and non-zero. 
D) None of the above. 
A) increase. 
B) decrease. 
C) stay constant and non-zero. 
D) None of the above.

Question 2

A 0.20-m-long metal rod has a radius of 3.0 cm and a resistance of 2.5 × 10−5 Ω.What is the resistivity of the metal?

Accepted Answer

A) 1.1E-8 Ω⋅m 
B) 3.5E-7 Ω⋅m 
C) 1.0E-8 Ω⋅m 
D) 1.8E-8 Ω⋅m 
E) 1.2E-7 Ω⋅m 
A) 1.1E-8 Ω⋅m 
B) 3.5E-7 Ω⋅m 
C) 1.0E-8 Ω⋅m 
D) 1.8E-8 Ω⋅m 
E) 1.2E-7 Ω⋅m

Question 3

A length L of wire has a voltage V across its ends while a current I runs through the wire.If a voltage 3V were applied to another length of this same wire from the same coil and the same current were found to run through it,what is the length of this second wire?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 4

In a certain material there is a current of 18 A flowing through a surface to the right,and there is an equal amount of positive and negative charge passing through the surface producing the current.How much negative charge passes through the surface?

Accepted Answer

A) 9 C/s toward the right 
B) 9 C/s toward the left 
C) 18 C/s toward the right 
D) 18 C/s toward the left 
E) 36 C/s toward the left 
A) 9 C/s toward the right 
B) 9 C/s toward the left 
C) 18 C/s toward the right 
D) 18 C/s toward the left 
E) 36 C/s toward the left

Question 5

If a 10-V battery,with negligible internal resistance,and a 15-Ω resistor are connected in series,what is the amount of electrical energy transformed to heat per coulomb of charge that flows through the circuit?

Accepted Answer

A) 0.67 J 
B) 1.5 J 
C) 10 J 
D) 150 J 
E) 25 J 
A) 0.67 J 
B) 1.5 J 
C) 10 J 
D) 150 J 
E) 25 J

Question 6

A wire 1 mm in diameter is connected to one end of a wire of the same material 2 mm in diameter of twice the length.A voltage source is connected to the wires and a current is passed through the wires.If it takes time T for the average conduction electron to traverse the 1-mm wire,how long does it take for such an electron to traverse the 2-mm wire?

Accepted Answer

A) T/4 
B) T 
C) 4T 
D) 8T 
A) T/4 
B) T 
C) 4T 
D) 8T

Question 7

Which is not a force?

Accepted Answer

A) gravity 
B) electrical force 
C) voltage 
D) friction 
A) gravity 
B) electrical force 
C) voltage 
D) friction

Question 8

An electric car is designed to run off a bank of 15-V batteries with total energy storage of 2.1 × 107 J.If the electric motor draws 4 200 W in moving the car at a steady speed of 14 m/s,how far will the car go before it is "out of juice?"

Accepted Answer

A) 35 km 
B) 70 km 
C) 140 km 
D) 110 km 
E) 18 km 
A) 35 km 
B) 70 km 
C) 140 km 
D) 110 km 
E) 18 km

Question 9

A light bulb with a tungsten filament is attached to a source of variable voltage.As the voltage is increased on the bulb,

Accepted Answer

A) the bulb's resistance decreases. 
B) the bulb's resistance increases. 
C) the current in the bulb decreases. 
D) the power dissipated remains constant. 
A) the bulb's resistance decreases. 
B) the bulb's resistance increases. 
C) the current in the bulb decreases. 
D) the power dissipated remains constant.

Question 10

The current in an electron beam in a cathode-ray tube is measured to be 50 µA.How many electrons hit the screen in 7.0 s? (e = 1.6 × 10−19 C)

Accepted Answer

A) 4.4 × 1011 electrons 
B) 3.5 × 1013 electrons 
C) 2.2 × 1015 electrons 
D) 3.1 × 1018 electrons 
E) 2.7 × 1017 electrons 
A) 4.4 × 1011 electrons 
B) 3.5 × 1013 electrons 
C) 2.2 × 1015 electrons 
D) 3.1 × 1018 electrons 
E) 2.7 × 1017 electrons

Question 11

If a certain resistor obeys Ohm's law,its resistance will change:

Accepted Answer

A) as the voltage across the resistor changes. 
B) as the current through the resistor changes. 
C) as the energy given off by the electrons in their collisions changes. 
D) none of the above,since resistance is a constant for the given resistor. 
A) as the voltage across the resistor changes. 
B) as the current through the resistor changes. 
C) as the energy given off by the electrons in their collisions changes. 
D) none of the above,since resistance is a constant for the given resistor.

Question 12

A steam turbine at an electric power plant delivers 4 500 kW of power to an electrical generator which converts 94% of this mechanical energy into electrical energy.What is the current delivered by the generator if it delivers at 3 500 V?

Accepted Answer

A) 7.3E+2 A 
B) 1.4E+3 A 
C) 1.2E+3 A 
D) 1.1E+3 A 
E) 8.3E+2 A 
A) 7.3E+2 A 
B) 1.4E+3 A 
C) 1.2E+3 A 
D) 1.1E+3 A 
E) 8.3E+2 A

Question 13

A high-voltage transmission line carries 1 400 A at 600 000 V.What is the power carried by the line?

Accepted Answer

A) 840 MW 
B) 370 MW 
C) 140 MW 
D) 84 MW 
E) 233 MW 
A) 840 MW 
B) 370 MW 
C) 140 MW 
D) 84 MW 
E) 233 MW

Question 14

A Nichrome wire has a radius of 1.3 mm and a resistivity of 1.5 × 10−6 Ω⋅m.If the wire carries a current of 1.8 A,what is the potential difference per unit length along this wire?

Accepted Answer

A) 0.19 V/m 
B) 0.51 V/m 
C) 0.66 V/m 
D) 6.4 V/m 
E) 5 V/m 
A) 0.19 V/m 
B) 0.51 V/m 
C) 0.66 V/m 
D) 6.4 V/m 
E) 5 V/m

Question 15

Carbon has a negative temperature coefficient of resistance of -0.5 × 10-3 (°C)−1.What temperature increase would result in a resistance decrease of 1.0% for a carbon resistor?

Accepted Answer

A) 2.0°C 
B) 20°C.. 
C) 20°C. 
D) 50°C 
E) 100°C 
A) 2.0°C 
B) 20°C.. 
C) 20°C. 
D) 50°C 
E) 100°C

Question 16

Materials having resistance changes as voltage or current varies are called:

Accepted Answer

A) ohmic. 
B) inohmic. 
C) nonohmic. 
D) deohmic. 
A) ohmic. 
B) inohmic. 
C) nonohmic. 
D) deohmic.

Question 17

A solar panel measures 80 cm × 57 cm.In direct sunlight,the panel delivers 3.1 A at 15 V.If the intensity of sunlight is 1 000 W/m2,what is the efficiency of the solar panel in converting solar energy into electrical energy?

Accepted Answer

A) 20% 
B) 15% 
C) 10% 
D) 5% 
E) 8% 
A) 20% 
B) 15% 
C) 10% 
D) 5% 
E) 8%

Question 18

When a superconductor's temperature drops below the critical temperature,its resistance:

Accepted Answer

A) equals that of a semiconductor of equal dimensions. 
B) increases by two. 
C) drops to zero. 
D) reduces to one half. 
A) equals that of a semiconductor of equal dimensions. 
B) increases by two. 
C) drops to zero. 
D) reduces to one half.

Question 19

When an electric current exists within a conducting wire,which of the following statements describes the condition of any accompanying electric field?

Accepted Answer

A) must be zero 
B) must be parallel to current flow 
C) must be anti-parallel (opposite direction)to current flow 
D) must be perpendicular to current flow 
A) must be zero 
B) must be parallel to current flow 
C) must be anti-parallel (opposite direction)to current flow 
D) must be perpendicular to current flow

Question 20

If a 600-W heater carries a current of 4.0 A,what is the voltage across the ends of the heating element?

Accepted Answer

A) 2 400 V 
B) 150 V 
C) 300 V 
D) 0.0067 V 
E) 4.9 V 
A) 2 400 V 
B) 150 V 
C) 300 V 
D) 0.0067 V 
E) 4.9 V

Exam 17: Current and Resistance

Consider some material that has been cooled until it has become a superconductor.If it is cooled even further its resistance will:

A 0.20-m-long metal rod has a radius of 3.0 cm and a resistance of 2.5 × 10−5 Ω.What is the resistivity of the metal?

A length L of wire has a voltage V across its ends while a current I runs through the wire.If a voltage 3V were applied to another length of this same wire from the same coil and the same current were found to run through it,what is the length of this second wire?

In a certain material there is a current of 18 A flowing through a surface to the right,and there is an equal amount of positive and negative charge passing through the surface producing the current.How much negative charge passes through the surface?

If a 10-V battery,with negligible internal resistance,and a 15-Ω resistor are connected in series,what is the amount of electrical energy transformed to heat per coulomb of charge that flows through the circuit?

Which is not a force?

An electric car is designed to run off a bank of 15-V batteries with total energy storage of 2.1 × 107 J.If the electric motor draws 4 200 W in moving the car at a steady speed of 14 m/s,how far will the car go before it is "out of juice?"

A light bulb with a tungsten filament is attached to a source of variable voltage.As the voltage is increased on the bulb,

The current in an electron beam in a cathode-ray tube is measured to be 50 µA.How many electrons hit the screen in 7.0 s? (e = 1.6 × 10−19 C)

If a certain resistor obeys Ohm's law,its resistance will change:

A steam turbine at an electric power plant delivers 4 500 kW of power to an electrical generator which converts 94% of this mechanical energy into electrical energy.What is the current delivered by the generator if it delivers at 3 500 V?

A high-voltage transmission line carries 1 400 A at 600 000 V.What is the power carried by the line?

A Nichrome wire has a radius of 1.3 mm and a resistivity of 1.5 × 10−6 Ω⋅m.If the wire carries a current of 1.8 A,what is the potential difference per unit length along this wire?

Carbon has a negative temperature coefficient of resistance of -0.5 × 10-3 (°C)−1.What temperature increase would result in a resistance decrease of 1.0% for a carbon resistor?

Materials having resistance changes as voltage or current varies are called:

A solar panel measures 80 cm × 57 cm.In direct sunlight,the panel delivers 3.1 A at 15 V.If the intensity of sunlight is 1 000 W/m2,what is the efficiency of the solar panel in converting solar energy into electrical energy?

When a superconductor's temperature drops below the critical temperature,its resistance:

When an electric current exists within a conducting wire,which of the following statements describes the condition of any accompanying electric field?

If a 600-W heater carries a current of 4.0 A,what is the voltage across the ends of the heating element?

Units, Trigonometry, and Vectors

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Newtons Laws of Motion

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Filters

A 0.20-m-long metal rod has a radius of 3.0 cm and a resistance of 2.5 × 10−⁵ Ω.What is the resistivity of the metal?

An electric car is designed to run off a bank of 15-V batteries with total energy storage of 2.1 × 10⁷ J.If the electric motor draws 4 200 W in moving the car at a steady speed of 14 m/s,how far will the car go before it is "out of juice?"

The current in an electron beam in a cathode-ray tube is measured to be 50 µA.How many electrons hit the screen in 7.0 s? (e = 1.6 × 10−¹⁹ C)

A Nichrome wire has a radius of 1.3 mm and a resistivity of 1.5 × 10−⁶ Ω⋅m.If the wire carries a current of 1.8 A,what is the potential difference per unit length along this wire?

Carbon has a negative temperature coefficient of resistance of -0.5 × 10^-3 (°C)−¹.What temperature increase would result in a resistance decrease of 1.0% for a carbon resistor?

A solar panel measures 80 cm × 57 cm.In direct sunlight,the panel delivers 3.1 A at 15 V.If the intensity of sunlight is 1 000 W/m²,what is the efficiency of the solar panel in converting solar energy into electrical energy?