Question 1

A hair dryer draws 1500 W,a curling iron draws 800 W,and an electric light fixture draws 500 W.If all three of these appliances are operating in parallel on a 120 V circuit,what is the total current drawn?

Accepted Answer

A)   23.3 A
B)   20.8 A
C)   36.7 A
D)   19.4 A

Question 2

A high voltage transmission line of diameter 2 cm and length 2 km carries a steady current of 1000 A.If the conductor is copper with a free charge density of 8 × 1028 electrons/m3,how long does it take one electron to travel the full length of the cable? (e = 1.6 × 10−19 C)

Accepted Answer

A)   8 × 102 s
B)   8 × 108 s
C)   8 × 106 s
D)   8 × 104 s

Question 3

What is the current through the 6-Ω resistor?

Accepted Answer

A)   1.0 A
B)   1.5A
C)   0.50 A
D)   2.0 A

Question 4

Five resistors each have resistance R.Three of the resistors are connected in series and this combination is then connected in parallel with the two other resistors which have been connected in series with each other.What is the equivalent resistance for this arrangement?

Accepted Answer

A)  
B)  
C)  
D)

Question 5

A tungsten wire is used to determine the melting point of indium.The resistance of the tungsten wire is 6.000 Ω at 20°C and increases to 9.700 Ω as the indium starts to melt.αtungsten = 4.50 × 10−3 (°C) −1.What is the melting temperature of indium?

Accepted Answer

A)   351°C
B)   731°C
C)   132°C
D)   157°C

Question 6

A metal wire has a resistance of 25.00 Ω under room temperature conditions of 25°C.When the wire is heated to 85°C the resistance increases by 1.95 Ω.What is the temperature coefficient of resistivity of this metal?

Accepted Answer

A)   1.3 × 10−3 (°
C)  −1
B)   1.5 × 10−3 (°
C)  −1
C)   5.0 × 10−4 (°
C)  −1
D)   2.5 × 10−3 (°
C)  −1

Question 7

If a light bulb has half the resistance of a 50-W lightbulb,what would be its wattage? Assume both bulbs are attached to the same 120-V circuit.

Accepted Answer

A)   More information is needed.
B)   25 W
C)   200 W
D)   100 W

Question 8

In circuits involving resistors and capacitors the quantity 63% often arises.Which of the following is equivalent to this quantity?

Accepted Answer

A)   e​-2
B)   1 - e​-1
C)   1 - e​-2
D)   e​-1

Question 9

A 100-W bulb and a 40-W bulb,each designed for an applied voltage of 120 V,are connected in series across a 120-V source.What are the voltages across the 100-W bulb and across the 40-W bulb?

Accepted Answer

A)   86 V,34 V
B)   30 V,90 V
C)   90 V,30 V
D)   34 V,86 V

Question 10

How long is a wire made from 200 cm3 of copper if its resistance is 8.5 ohms? The resistivity of copper is 1.7 × 10-5 Ω·m.

Accepted Answer

A)   10 m
B)   2.2 × 102 m
C)   7.1 m
D)   3.0 × 103 m

Question 11

Three wires of the same diameter and length are made from three different metals: copper (ρ​ = 1.7 × 10-8 Ω·m) ,aluminum (ρ​ = 2.7 × 10-8 Ω·m) ,and silver (ρ​ = 1.6 × 10-8 Ω·m) .Which wire has the least resistance?

Accepted Answer

A)   the aluminum wire
B)   the silver wire
C)   the copper wire
D)   Since insufficient information is given to find the resistance of each wire,one cannot find the answer.

Question 12

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 6.0 × 107 J.If the electric motor draws 6000 W in moving the car at a steady speed of 10 m/s,how far will the car go before it is "out of juice?"

Accepted Answer

A)   150 km
B)   50 km
C)   100 km
D)   25 km

Question 13

A metal wire has a resistance of 10.00 Ω at a temperature of 20.0°C.If the same wire has a resistance of 10.55 Ω at 90°C,what is the resistance when its temperature is 0.0°C?

Accepted Answer

A)   13.8 Ω
B)   9.69 Ω
C)   9.84 Ω
D)   0.70 Ω

Question 14

A 100-W light bulb is in a socket supplied with 120 V.What is the current in the bulb?

Accepted Answer

A)   7200 A
B)   0.83 A
C)   1.4 A
D)   0.50 A

Question 15

Two resistors of values 6.0 and 12.0 Ω are connected in parallel.This combination in turn is hooked in series with an 8.0-Ω resistor and a 24-V battery.What is the current in the 12-Ω resistor?

Accepted Answer

A)   1.3 A
B)   4.0 A
C)   12 A
D)   0.67 A

Question 16

If a 500-W heater carries a current of 2.00 A,what is the voltage across the ends of the heating element?

Accepted Answer

A)   2000 V
B)   125 V
C)   0.008 V
D)   250 V

Question 17

A lightbulb drawing a current of 0.60 A is run for 2.0 hours.How many electrons pass through the bulb during this process?

Accepted Answer

A)   2.7 × 1022
B)   1.4 × 1019
C)   5.4 × 1025
D)   4.3 × 103

Question 18

A water pump draws about 4.4 A when connected to 240 V.What is the cost (with electrical energy at 9 cents per kWh) of running the pump for 10 h?

Accepted Answer

A)   82 cents
B)   8.0 cents
C)   95 cents
D)   15 cents

Question 19

An electric clothes dryer draws 20 A at 220 V.If the clothes put into the dryer have a mass of 7.0 kg when wet and 3.0 kg dry,how long does it take to dry the clothes? (Assume all heat energy goes into vaporizing water,Lv = 2.26 × 106 J/kg. )

Accepted Answer

A)   55 min
B)   26 min
C)   16 min
D)   34 min

Question 20

Three 3.0-Ω resistors are connected in parallel to a 12.0-V battery.What is the current in any one of the resistors?

Accepted Answer

A)   0.75 A
B)   12 A
C)   4.0 A
D)   1.3 A

Exam 19: Magnetism Magnets: Part A

A tungsten wire is used to determine the melting point of indium.The resistance of the tungsten wire is 6.000 Ω at 20°C and increases to 9.700 Ω as the indium starts to melt.αtungsten = 4.50 × 10−3 (°C) −1.What is the melting temperature of indium?

Correct AnswerverifiedShow Answer

A water pump draws about 4.4 A when connected to 240 V.What is the cost (with electrical energy at 9 cents per kWh) of running the pump for 10 h?

Correct AnswerverifiedShow Answer

If a light bulb has half the resistance of a 50-W lightbulb,what would be its wattage? Assume both bulbs are attached to the same 120-V circuit.

Correct AnswerverifiedShow Answer

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 6.0 × 107 J.If the electric motor draws 6000 W in moving the car at a steady speed of 10 m/s,how far will the car go before it is "out of juice?"

Correct AnswerverifiedShow Answer

A lightbulb drawing a current of 0.60 A is run for 2.0 hours.How many electrons pass through the bulb during this process?

Correct AnswerverifiedShow Answer

Five resistors each have resistance R.Three of the resistors are connected in series and this combination is then connected in parallel with the two other resistors which have been connected in series with each other.What is the equivalent resistance for this arrangement?

Correct AnswerverifiedShow Answer

A metal wire has a resistance of 25.00 Ω under room temperature conditions of 25°C.When the wire is heated to 85°C the resistance increases by 1.95 Ω.What is the temperature coefficient of resistivity of this metal?

Correct AnswerverifiedShow Answer

Three 3.0-Ω resistors are connected in parallel to a 12.0-V battery.What is the current in any one of the resistors?

Correct AnswerverifiedShow Answer

If a 500-W heater carries a current of 2.00 A,what is the voltage across the ends of the heating element?

Correct AnswerverifiedShow Answer

A metal wire has a resistance of 10.00 Ω at a temperature of 20.0°C.If the same wire has a resistance of 10.55 Ω at 90°C,what is the resistance when its temperature is 0.0°C?

Correct AnswerverifiedShow Answer

A 100-W light bulb is in a socket supplied with 120 V.What is the current in the bulb?

Correct AnswerverifiedShow Answer

How long is a wire made from 200 cm3 of copper if its resistance is 8.5 ohms? The resistivity of copper is 1.7 × 10-5 Ω·m.

Correct AnswerverifiedShow Answer

A hair dryer draws 1500 W,a curling iron draws 800 W,and an electric light fixture draws 500 W.If all three of these appliances are operating in parallel on a 120 V circuit,what is the total current drawn?

Correct AnswerverifiedShow Answer

Three wires of the same diameter and length are made from three different metals: copper (ρ​ = 1.7 × 10-8 Ω·m) ,aluminum (ρ​ = 2.7 × 10-8 Ω·m) ,and silver (ρ​ = 1.6 × 10-8 Ω·m) .Which wire has the least resistance?

Correct AnswerverifiedShow Answer

What is the current through the 6-Ω resistor?

Correct AnswerverifiedShow Answer

A 100-W bulb and a 40-W bulb,each designed for an applied voltage of 120 V,are connected in series across a 120-V source.What are the voltages across the 100-W bulb and across the 40-W bulb?

Correct AnswerverifiedShow Answer

An electric clothes dryer draws 20 A at 220 V.If the clothes put into the dryer have a mass of 7.0 kg when wet and 3.0 kg dry,how long does it take to dry the clothes? (Assume all heat energy goes into vaporizing water,Lv = 2.26 × 106 J/kg. )

Correct AnswerverifiedShow Answer

Two resistors of values 6.0 and 12.0 Ω are connected in parallel.This combination in turn is hooked in series with an 8.0-Ω resistor and a 24-V battery.What is the current in the 12-Ω resistor?

Correct AnswerverifiedShow Answer

A high voltage transmission line of diameter 2 cm and length 2 km carries a steady current of 1000 A.If the conductor is copper with a free charge density of 8 × 1028 electrons/m3,how long does it take one electron to travel the full length of the cable? (e = 1.6 × 10−19 C)

Correct AnswerverifiedShow Answer

In circuits involving resistors and capacitors the quantity 63% often arises.Which of the following is equivalent to this quantity?

Correct AnswerverifiedShow Answer

A tungsten wire is used to determine the melting point of indium.The resistance of the tungsten wire is 6.000 Ω at 20°C and increases to 9.700 Ω as the indium starts to melt.α_tungsten = 4.50 × 10−³ (°C) −¹.What is the melting temperature of indium?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 6.0 × 10⁷ J.If the electric motor draws 6000 W in moving the car at a steady speed of 10 m/s,how far will the car go before it is "out of juice?"

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

How long is a wire made from 200 cm³ of copper if its resistance is 8.5 ohms? The resistivity of copper is 1.7 × 10^-5 Ω·m.

Correct Answer
verified

Correct Answer
verified

Three wires of the same diameter and length are made from three different metals: copper (ρ = 1.7 × 10^-8 Ω·m) ,aluminum (ρ = 2.7 × 10^-8 Ω·m) ,and silver (ρ = 1.6 × 10^-8 Ω·m) .Which wire has the least resistance?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

An electric clothes dryer draws 20 A at 220 V.If the clothes put into the dryer have a mass of 7.0 kg when wet and 3.0 kg dry,how long does it take to dry the clothes? (Assume all heat energy goes into vaporizing water,L_v = 2.26 × 10⁶ J/kg. )

Correct Answer
verified

Correct Answer
verified

A high voltage transmission line of diameter 2 cm and length 2 km carries a steady current of 1000 A.If the conductor is copper with a free charge density of 8 × 10²⁸ electrons/m³,how long does it take one electron to travel the full length of the cable? (e = 1.6 × 10−¹⁹ C)

Correct Answer
verified

Correct Answer
verified