Question 1

The figure shows electrons passing through a resistor.The arrow shows the direction in which the electrons are moving.Which of the following statements are correct? (There could be more than one correct choice.)

Accepted Answer

A) The electrons are moving slower at point b than at point a. 
B) The electric potential is higher at point b than at point a. 
C) The electric potential is lower at point b than at point a. 
D) The system electrons-metal is losing electric potential energy as the electrons move through the resistor from a to b. 
E) The speed of the electrons at point b is the same as it is at point a.

Question 2

A 22-A current flows into a parallel combination of 4.0-Ω,6.0-Ω,and 12-Ω resistors.What current flows through the 12-Ω resistor?

Accepted Answer

A) 18 A 
B) 11 A 
C) 7.3 A 
D) 3.7 A

Question 3

Kirchhoff's loop rule is a statement of

Accepted Answer

A) the law of conservation of momentum. 
B) the law of conservation of charge. 
C) the law of conservation of energy. 
D) the law of conservation of angular momentum. 
E) Newton's second law.

Question 4

A multiloop circuit is shown in the figure,but some quantities are not labeled.Find the current I1 if the batteries are ideal.(It is not necessary to solve the entire circuit.)

Accepted Answer

A) 0 A 
B) +0.2 A 
C) +0.4 A 
D) -0.2 A 
E) -0.4 A

Question 5

If emf of the ideal battery is V = 4.0 V,what is the current through R6 for the circuit shown in the figure?

Accepted Answer

A) 0.0077 A 
B) 0.017 A 
C) 0.040 A 
D) 4.0 A

Question 6

During a period of high power demand,the voltage output of the power company is reduced by 5.0%.By what percentage is the power in a resistor decreased?

Accepted Answer

A) 2.5% 
B) 5.0% 
C) 10% 
D) 15% 
E) 90%

Question 7

A 120-m long metal wire having a resistivity of 1.68 × 10-8 Ω ∙ m has a resistance of 6.0 Ω.What is the diameter of the wire?

Accepted Answer

A) 0.065 mm 
B) 0.65 mm 
C) 0.65 cm 
D) 0.65 m

Question 8

A number of resistors are connected across points A and B as shown in the figure.What is the equivalent resistance between points A and B?

Accepted Answer

A) 4 Ω 
B) 6 Ω 
C) 8 Ω 
D) 10 Ω 
E) 12 Ω

Question 9

The nichrome heating element in an electric drier operates on 240 V and generates thermal energy at the rate of 2.0 kW.The heating element shorts out and,in repairing it,the repairman shortens the nichrome wire by 10%.(Assume the temperature is unchanged.In reality,the resistivity of the wire will depend on its temperature.)What effect will the repair have on the power dissipated in the heating element?

Accepted Answer

A) The power is still 2.0 kW. 
B) The power increases to 2.2 kW. 
C) The power decreases to 1.8 kW. 
D) None of the given answers is correct.

Question 10

The following three appliances are connected in parallel across an ideal 120-V dc power source: 1200-W toaster,650-W coffee pot,and 600-W microwave.If all were operated at the same time what total current would they draw from the source?

Accepted Answer

A) 4.0 A 
B) 5.0 A 
C) 10 A 
D) 20 A

Question 11

Draw a circuit with two batteries,a resistor between them,and a capacitor in parallel with the resistor.The batteries are connected negative pole to positive pole.

Accepted Answer

A)  
B)  
C)  
D)

Question 12

A multiloop circuit is shown in the figure,but some quantities are not labeled.Find the current I2 if the batteries are ideal.(It is not necessary to solve the entire circuit.)

Accepted Answer

A) +0.1 A 
B) +0.3 A 
C) +0.5 A 
D) -0.1 A 
E) -0.3 A

Question 13

A battery has an emf ε = 12 V and an internal resistance r = 2.0 Ω,as shown in the figure.When a 3.0-Ω cable is connected across the battery terminals a and b,the rate at which chemical energy in the battery is depleted is closest to

Accepted Answer

A) 24 W. 
B) 27 W. 
C) 29 W. 
D) 32 W. 
E) 34 W.

Question 14

A kilowatt-hour is equivalent to

Accepted Answer

A) 1000 W. 
B) 3600 J. 
C) 3,600,000 J/s. 
D) 3,600,000 J. 
E) 3600 J/s

Question 15

You buy a AA battery in the store,and it is marked 1.5 V.If this marking is strictly accurate,while this battery is fresh

Accepted Answer

A) its terminal voltage will be more than 1.5 V when it is used in a circuit. 
B) its terminal voltage will be less than 1.5 V when it is used in a circuit. 
C) its terminal voltage will be 1.5 V when it is used in a circuit.

Question 16

When there is electric current through an ionic liquid such as salty water,the moving charges are

Accepted Answer

A) only protons. 
B) only electrons. 
C) only negative ions. 
D) only positive ions. 
E) both positive and negative ions.

Question 17

What potential difference is required across an 8.0-Ω resistor to cause a 2.0 A current through it?

Accepted Answer

The answer of What potential difference is required across an...

Question 18

For the circuit shown in the figure,what is the power dissipated in the 2.0-Ω resistor? All the numbers shown are accurate to three significant figures.

Accepted Answer

A) 5.33 W 
B) 8.00 W 
C) 6.67 W 
D) 2.67 W 
E) 3.56 W

Question 19

The power rating of a 400-Ω resistor is 0.25 W.What is the maximum voltage you can safely connect across its ends?

Accepted Answer

A) 10 V 
B) 20 V 
C) 30 V 
D) 40 V 
E) 50 V

Question 20

For the circuit shown in the figure,both batteries are ideal.What is the current through the solid wire connecting the upper left and lower left corners of the circuit?

Accepted Answer

A) 0.25 A 
B) 0.50 A 
C) 0.75 A 
D) 1.0 A

Exam 17: Dc Circuits