Exam 21: Electric Current and Direct-Current Circuits

Three resistors with resistances of 2.0 Ω,6.0 Ω,and 12 Ω are connected across an ideal dc voltage source V,as shown in the figure.If the total current in the circuit is I = 5.0 A,what is the current through the 12-Ω resistor?

When 5.00 A is flowing through an 10.0-Ω device,how much power is being dissipated in the device?

Three capacitors are connected as shown in the figure.What is the equivalent capacitance between points A and B?

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?

A 120-Ω laboratory resistor is rated at 0.25 W.How much current can safely flow through the resistor?

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

The network shown is assembled with uncharged capacitors X ,Y,and Z,with And The switches S₁ and S₂ are initially open,and a potential difference V_ab = 120 V is applied between points a and b.After the network is assembled,switch S₁ is then closed,but switch S₂ is kept open.What is the final potential difference across capacitor Z?

The resistivity of the material of a wire is 1.76 × 10^-8 Ω ∙ m.If the diameter of the wire is 2.00 mm and its length is 2.00 m,what is its resistance?

When unequal resistors are connected in series across an ideal battery,

A resistor is made out of a wire having a length L.When the ends of the wire are attached across the terminals of an ideal battery having a constant voltage V₀ across its terminals,a current I flows through the wire.If the wire were cut in half,making two wires of length L/2,and both wires were attached across the terminals of the battery (the right ends of both wires attached to one terminal,and the left ends attached to the other terminal),how much current would the battery put out?

A kilowatt-hour is equivalent to

What is the equivalent resistance of the circuit shown in the figure? The battery is ideal and all resistances are accurate to 3 significant figures.

For the graph shown in the figure,what physical quantity does the slope of the graph represent for a dc circuit?

A 1.0-μF capacitor is charged until it acquires a potential difference of 900.0 V. Across its plates,and then the emf source is removed.If the capacitor is then discharged through a 500.0-kΩ. Resistance,what is the voltage drop across the capacitor 9.0 ms. After beginning the discharge?

For the circuit shown in the figure,C = 13 µF and R = 7.6 MΩ.Initially the switch S is open with the capacitor charged to a voltage of 80 V.The switch is then closed at time t = 0.00 s.What is the charge on the capacitor 40 s after closing the switch?

What is the potential drop from point A to point B for the circuit shown in the figure? The battery is ideal,and all the numbers are accurate to two significant figures.

What is the resistance of 1.0 m of a solid cylindrical metal cable having a diameter of 0.40 inches and a resistivity of 1.68 × 10^-8 Ω ∙ m?

A capacitor C is connected in series with a resistor R across a battery and an open switch.If a second capacitor of capacitance 2C is connected in series with the first one,the time constant of the new RC circuit will be

In the circuit shown in the figure,R₁ = 10 Ω,R₂ = 12 Ω,R₃ = 20 Ω,V₁ = 1.0 V,V₂ = 7.0 V,and the batteries are both ideal.What is the current through R₁?

A simple circuit has a total resistance of 30 Ω.If a 2.0-A current is maintained in this circuit,how much energy is dissipated in this circuit in 4.0 seconds?