Exam 5: Electric Current and Direct-Current Circuits

A potential difference of 120 V produces a current of 8.0 A in the heating element of a toaster. What is the resistance of this heating element while the toaster is carrying this current?

Given a sensitive galvanometer G and a collection of resistances of various values, a voltmeter can be constructed by

A 20- $\mu$ F capacitor is charged to 200 V and is then connected across a 1000- $\Omega$ resistor. The time constant for this circuit is approximately

A comparison of the power losses (P₁, P₂, or P₃) in the resistors of the circuit in the diagram shows that, if R₁ = R₂ = R₃,

The conservation of energy in an electric circuit is closely related to which of the following?

Tony charges a capacitor and then discharges it through a resistor. He notices that, after two time constants, the voltage across the capacitor has decreased to _____ of its value just prior to the initiation of the discharge.

The current I through the battery in this circuit is

If three resistors in the various configurations shown are placed in a simple circuit, the configuration in which all three resistors carry the same current is

If a current of 2.0 A is flowing from point a to point b, the potential difference between the points is

Consider a conductor for which R = the resistance in ohms, $\rho$ = the resistivity, A = the cross sectional area in m², and L = the length in meters. Which of the following is an expression for $\rho$ ?

The forward current for a pn-diode is given by where I₀ and V₀ are constants. If I₀ = 4 $\mu$ A and V₀ = 1.5 V, what is the ratio of the current for V = 2 V to 0)5 V?

The same potential difference is applied across two wires. Wire A carries twice the current of wire B. If the resistance of wire B is R, what is the resistance of wire A?

What is the current through the circuit in the figure?

The current in a wire varies with time according to the relation I = 4 + 3t² Where I is in amperes and t is in seconds. The number of coulombs of charge that pass a cross section of the wire between t = 3 s and t = 5 s is

Use the diagram below for the next two problems: -The diagram shows the current versus voltage for a diode. The region which has the highest resistance is

The curves on the graph represent the current versus the potential difference for various conductors. The conductor whose behavior is described by Ohm's law is

You connect resistors of 2 $\Omega$ , 3 $\Omega$ , and 6 $\Omega$ in parallel across a battery. The current through the 6- $\Omega$ resistor is 3 A. What are the currents in the other two resistors?

A 12-V battery has an internal resistance of 0.20 $\Omega$ . If the battery is being charged by a current of 30 A, the magnitude of the potential difference between its terminals is

A current of 0.50 A passes through a lamp with a resistance of 600 $\Omega$ . The power supplied to this lamp is

Since you cannot afford expensive cable to hook up between your loudspeaker and music amplifier, you try some common 14-gauge (diameter = 1.628 mm) copper wire. If the total length of the wire (there and back) used for each speaker to amplifier hookup was 10 m, then calculate the resistance in the wire for one channel. ( $\rho$ (Cu) = 1.7 *10^-8 $\Omega$ /m)