Question 1

A metal wire has a resistance of 15.50 Ω at a temperature of 25.0°C.If the same wire has a resistance of 15.9 Ω at 90.0°C,what is the resistance when its temperature is −32.0°C?

Accepted Answer

A)  2.26 Ω 
B)  15.1 Ω 
C)  5.68 Ω 
D)  43.8 Ω 
E)  14.2 Ω

Question 2

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 4% for a carbon resistor?

Accepted Answer

A)  8°C 
B)  80°C 
C)  19°C 
D)  13°C 
E)  ​400°C

Question 3

Wire A and Wire B are each carrying the same current.If the diameter of Wire A is twice that of Wire B,how does the drift velocity vdA in Wire A compare to that in in Wire B?

Accepted Answer

A)  vdA = vdB 
B)  vdA = 2 vdB 
C)  vdA = vdB /2 
D)  vdA = vdB /4

Question 4

Which is not a force?

Accepted Answer

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

Question 5

The temperature coefficient of resistivity is a quantity that is:

Accepted Answer

A)  always positive. 
B)  always non-negative. 
C)  sometimes negative. 
D)  represented by the symbol σ.

Question 6

The unit of electric current,the ampere,is equivalent to which of the following?

Accepted Answer

A)  V⋅Ω 
B)  V/Ω 
C)  Ω⋅m 
D)  V/s

Question 7

An 5.00-Ω resistor is dissipating 80 watts.What are the current through it and the difference of potential across it?
​

Accepted Answer

A)  16 A,20 V 
B)  20 A,4 V 
C)  4 A,20 V 
D)  4 A,16 V 
E)  16 A,80 V

Question 8

A flashlight bulb operating at a voltage of 3 V has a resistance of 10 Ω.How many electrons pass through the bulb filament per second (e = 1.6 × 10−19 C)?

Accepted Answer

A)  0.5 × 1016 
B)  4.8 × 1021 
C)  5.3 × 1017 
D)  1.9 × 1018 
E)  ​2.1 × 1020

Question 9

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 3.0 × 107 J.If the electric motor draws 5,400 W,what current will be delivered to the motor?
​

Accepted Answer

A)  450 A 
B)  225 A 
C)  675 A 
D)  338 A 
E)  ​113 A

Question 10

A 24-Ω platinum wire at 25°C with a temperature coefficient of resistivity of 3.9 × 10−3 (°C)−1 will have what resistance at 95°C?

Accepted Answer

A)  17 Ω 
B)  19 Ω 
C)  31 Ω 
D)  24 Ω 
E)  ​7 Ω

Question 11

If electrical energy costs 4 cents per kWh,what does it cost to heat 210 kg water from 30°C to 65°C? (The specific heat of water = 103 cal/kg⋅°C and 1.0 cal = 4.186 J. )

Accepted Answer

A)  87 cents 
B)  47 cents 
C)  40 cents 
D)  20 cents 
E)  ​59 cents

Question 12

A Nichrome wire has a radius of 0.9 mm and a resistivity of 1.5 × 10−6 Ω⋅m.What is the resistance per unit length of this wire?

Accepted Answer

A)  0.5 Ω/m 
B)  3.8 Ω/m 
C)  5.8 Ω/m 
D)  0.6 Ω/m 
E)  ​1.9 Ω/m

Question 13

If a 12-V battery,with negligible internal resistance,and an 20-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)  0.6 J 
B)  2 J 
C)  12 J 
D)  240 J 
E)  ​32 J

Question 14

A 400-W heater carries a current of 4.0 A.How much does it cost to operate the heater for 50 min if electrical energy costs 6 cents per kWh?

Accepted Answer

A)  2 cents 
B)  12 cents 
C)  2.9 cents 
D)  0.1 cents 
E)  ​40 cents

Question 15

A water pump draws about 3.7 A when connected to 200 V.What is the cost (with electrical energy at 9 cents per kWh)of running the pump for 12 h?

Accepted Answer

A)  5.8 cents 
B)  21 cents 
C)  79.9 cents 
D)  159.8 cents 
E)  ​59.9 cents

Question 16

A solar panel measures 70 cm × 54 cm.In direct sunlight,the panel delivers 3.1 A at 12 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%

Question 17

When you flip a switch to turn on a light,the delay before the light turns on is determined by:

Accepted Answer

A)  the number of electron collisions per second in the wire. 
B)  the drift speed of the electrons in the wire. 
C)  the speed of the electric field moving in the wire. 
D)  none of these,since the light comes on instantly.

Question 18

When current is flowing in a superconductor,which statement is not true?

Accepted Answer

A)  A battery is needed to keep the current going. 
B)  Electrical charges are moving. 
C)  The resistance is zero. 
D)  No power is given off in the form of heat.

Question 19

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

Accepted Answer

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

Question 20

Replacing a wire resistor with another of the same material and length but with three times the diameter will have the effect of changing the resistance by what factor?

Accepted Answer

A)  1/3 
B)  1/9 
C)  3 
D)  9

Exam 17: Current and Resistance Electric Current

A metal wire has a resistance of 15.50 Ω at a temperature of 25.0°C.If the same wire has a resistance of 15.9 Ω at 90.0°C,what is the resistance when its temperature is −32.0°C?

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 4% for a carbon resistor?

Wire A and Wire B are each carrying the same current.If the diameter of Wire A is twice that of Wire B,how does the drift velocity v_dA in Wire A compare to that in in Wire B?

Which is not a force?

The temperature coefficient of resistivity is a quantity that is:

The unit of electric current,the ampere,is equivalent to which of the following?

An 5.00-Ω resistor is dissipating 80 watts.What are the current through it and the difference of potential across it?

A flashlight bulb operating at a voltage of 3 V has a resistance of 10 Ω.How many electrons pass through the bulb filament per second (e = 1.6 × 10−¹⁹ C) ?

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 3.0 × 10⁷ J.If the electric motor draws 5,400 W,what current will be delivered to the motor?

A 24-Ω platinum wire at 25°C with a temperature coefficient of resistivity of 3.9 × 10−³ (°C) −¹ will have what resistance at 95°C?

If electrical energy costs 4 cents per kWh,what does it cost to heat 210 kg water from 30°C to 65°C? (The specific heat of water = 10³ cal/kg⋅°C and 1.0 cal = 4.186 J. )

A Nichrome wire has a radius of 0.9 mm and a resistivity of 1.5 × 10−⁶ Ω⋅m.What is the resistance per unit length of this wire?

If a 12-V battery,with negligible internal resistance,and an 20-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?

A 400-W heater carries a current of 4.0 A.How much does it cost to operate the heater for 50 min if electrical energy costs 6 cents per kWh?

A water pump draws about 3.7 A when connected to 200 V.What is the cost (with electrical energy at 9 cents per kWh) of running the pump for 12 h?

A solar panel measures 70 cm × 54 cm.In direct sunlight,the panel delivers 3.1 A at 12 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 you flip a switch to turn on a light,the delay before the light turns on is determined by:

When current is flowing in a superconductor,which statement is not true?

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

Replacing a wire resistor with another of the same material and length but with three times the diameter will have the effect of changing the resistance by what factor?

Exam 17: Current and Resistance Electric Current

A metal wire has a resistance of 15.50 Ω at a temperature of 25.0°C.If the same wire has a resistance of 15.9 Ω at 90.0°C,what is the resistance when its temperature is −32.0°C?

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 4% for a carbon resistor?

Wire A and Wire B are each carrying the same current.If the diameter of Wire A is twice that of Wire B,how does the drift velocity vdA in Wire A compare to that in in Wire B?

Which is not a force?

The temperature coefficient of resistivity is a quantity that is:

The unit of electric current,the ampere,is equivalent to which of the following?

An 5.00-Ω resistor is dissipating 80 watts.What are the current through it and the difference of potential across it? ​

A flashlight bulb operating at a voltage of 3 V has a resistance of 10 Ω.How many electrons pass through the bulb filament per second (e = 1.6 × 10−19 C) ?

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 3.0 × 107 J.If the electric motor draws 5,400 W,what current will be delivered to the motor? ​

A 24-Ω platinum wire at 25°C with a temperature coefficient of resistivity of 3.9 × 10−3 (°C) −1 will have what resistance at 95°C?

If electrical energy costs 4 cents per kWh,what does it cost to heat 210 kg water from 30°C to 65°C? (The specific heat of water = 103 cal/kg⋅°C and 1.0 cal = 4.186 J. )

A Nichrome wire has a radius of 0.9 mm and a resistivity of 1.5 × 10−6 Ω⋅m.What is the resistance per unit length of this wire?

If a 12-V battery,with negligible internal resistance,and an 20-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?

A 400-W heater carries a current of 4.0 A.How much does it cost to operate the heater for 50 min if electrical energy costs 6 cents per kWh?

A water pump draws about 3.7 A when connected to 200 V.What is the cost (with electrical energy at 9 cents per kWh) of running the pump for 12 h?

A solar panel measures 70 cm × 54 cm.In direct sunlight,the panel delivers 3.1 A at 12 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 you flip a switch to turn on a light,the delay before the light turns on is determined by:

When current is flowing in a superconductor,which statement is not true?

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

Replacing a wire resistor with another of the same material and length but with three times the diameter will have the effect of changing the resistance by what factor?

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 4% for a carbon resistor?

Wire A and Wire B are each carrying the same current.If the diameter of Wire A is twice that of Wire B,how does the drift velocity v_dA in Wire A compare to that in in Wire B?

An 5.00-Ω resistor is dissipating 80 watts.What are the current through it and the difference of potential across it?

A flashlight bulb operating at a voltage of 3 V has a resistance of 10 Ω.How many electrons pass through the bulb filament per second (e = 1.6 × 10−¹⁹ C) ?

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 3.0 × 10⁷ J.If the electric motor draws 5,400 W,what current will be delivered to the motor?

A 24-Ω platinum wire at 25°C with a temperature coefficient of resistivity of 3.9 × 10−³ (°C) −¹ will have what resistance at 95°C?

If electrical energy costs 4 cents per kWh,what does it cost to heat 210 kg water from 30°C to 65°C? (The specific heat of water = 10³ cal/kg⋅°C and 1.0 cal = 4.186 J. )

A Nichrome wire has a radius of 0.9 mm and a resistivity of 1.5 × 10−⁶ Ω⋅m.What is the resistance per unit length of this wire?

A solar panel measures 70 cm × 54 cm.In direct sunlight,the panel delivers 3.1 A at 12 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?