Exam 27: Current and Resistance

When a voltage difference is applied to a piece of metal wire,a current flows through it.If this metal wire is now replaced with a silver wire having twice the diameter of the original wire,how much current will flow through the silver wire? The lengths of both wires are the same,and the voltage difference remains unchanged.(The resistivity of the original metal is 1.68 × 10^-8 Ω ∙ m,and the resistivity of silver is 1.59 × 10^-8 Ω ∙ m.)

What length of a certain metal wire of diameter 0.15 mm is needed for the wire to have a resistance of 15 Ω? The resistivity of this metal is 1.68 × 10^-8 Ω ∙ m.

In an electroplating process,copper (ionic charge +2e,atomic weight 63.6 g/mol)is deposited using a current of 10.0 A.What mass of copper is deposited in 10.0 minutes? Avogadro's number is 6.022 × 10²³ molecules/mol and e = 1.60 × 10^-19 C.

In a certain electroplating process gold is deposited by using a current of 14.0 A for 19 minutes.A gold ion,Au⁺,has a mass of approximately 3.3 × 10^-22 g.How many grams of gold are deposited by this process?

A wire has a cross-sectional area of 0.10 mm².If there are 4.0 × 10²⁸ atoms per cubic meter in this wire,and if each atom contributes 2 free electrons,what is the drift velocity of the electrons when the current in the wire is 6.0 A? (e = 1.60 × 10^-19 C)

If the current density in a wire or radius R is given by J = kr,0 < r < R,what is the current in the wire?

A tube of mercury with resistivity 9.84 × 10^-7 Ω ∙ m has an electric field inside the column of mercury of magnitude 23 N/C that is directed along the length of the tube.How much current is flowing through this tube if its diameter is 1.0 mm?

A wire of resistivity ρ must be replaced in a circuit by a wire of the same material but 4 times as long.If,however,the resistance of the new wire is to be the same as the resistance of the original wire,the diameter of the new wire must be

The figure shows a steady electric current passing through a wire with a narrow region.What happens to the drift velocity of the moving charges as they go from region A to region B and then to region C?

A certain fuse "blows" if the current in it exceeds 1.0 A,at which instant the fuse melts with a current density of What is the diameter of the wire in the fuse?

Two cables of the same length are made of the same material,except that one cable has twice the diameter of the other cable.When the same potential difference is maintained across both cables,which of the following statements are true? (There may be more than one correct choice.)

Building codes usually limit the current carried by a No.14 copper wire to 15 A.Many household circuits are wired with this size wire.What is the drift velocity of the electrons in this case? The diameter of this wire is 1.6 mm.Assume one conduction electron per atom in copper.The atomic weight of copper is 63.3 g/mol and its density is 8900 kg/m³.Avogadro's number is 6.022 × 10²³ molecules/mol and e = 1.60 × 10^-19 C.

The current supplied by a battery as a function of time is What is the total number of electrons transported from the positive electrode to the negative electrode from the time the battery is first used until it is essentially dead? (e = 1.60 × 10^-19 C)

If a current of 2.4 A is flowing in a cylindrical wire of diameter 2.0 mm,what is the average current density in this wire?

A proton beam that carries a total current of 1.3 mA has 10.0 mm diameter.The current density in the proton beam increases linearly with distance from the center.This is expressed mathematically as J(r)= J₀ (r/R),where R is the radius of the beam and J₀ is the current density at the edge.Determine the value of J₀.

The figure shows two connected wires that are made of the same material.The current entering the wire on the left is 2.0 A and in that wire the electron drift speed is v_d.What is the electron drift speed in the wire on the right side?

A narrow copper wire of length L and radius b is attached to a wide copper wire of length L and radius 2b,forming one long wire of length 2L.This long wire is attached to a battery,and a current is flowing through it.If the electric field in the narrow wire is E,the electric field in the wide wire is

A silver wire has a cross sectional area A = 2.0 mm².A total of 9.4 × 10¹⁸ electrons pass through the wire in 3.0 s.The conduction electron density in silver is 5.8 × 10²⁸ electrons/m³ and e = 1.60 × 10^-19 C.What is the drift velocity of these electrons?

A 2.0 mm diameter wire of length 20 m has a resistance of 0.25 Ω.What is the resistivity of the wire?

How much current will be flowing through a 40.0 m length of cylindrical metal wire with radius 0.0 mm if it is connected to a source supplying 16.0 V? The resistivity of this metal is 1.68 × 10^-8 Ω ∙ m.