Exam 25: Current,resistance,and Electromotive Force

The resistivity of gold is at room temperature.A gold wire that is 0.9 mm in diameter and 14 cm long carries a current of 940 mA.What is the electric field in the wire?

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.)

A gold wire that is 1.8 mm in diameter and 15 cm long carries a current of 260 mA.How many electrons per second pass a given cross section of the wire? (e = 1.60 × 10^-19C

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 1500-W heater is connected to a 120-V line.How much heat energy does it produce in 2.0 hours?

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.

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

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 piece of wire 58.4 cm long carries a current I when a voltage V is applied across its ends at a temperature of 0°C.If the resistivity of the material of which the wire is made varies with temperature as shown in the graph in the figure,what length of the same diameter wire is needed so that the same current flows when the same voltage is applied at temperature 400°C?

A cylindrical wire has a resistance R and resistivity ρ.If its length and diameter are BOTH cut in half -what will be its resistivity?

The emf and the internal resistance of a battery are as shown in the figure.If a current of 8.3 A is drawn from the battery when a resistor R is connected across the terminals ab of the battery,what is the power dissipated by the resistor R?

As current flows through a uniform wire,the wire gets hotter because the electrons stop moving and therefore transform their lost kinetic energy into thermal energy in the wire.

The diameter of a 12-gauge copper wire is 0.081 in.The maximum safe current it can carry (in order to prevent fire danger in building construction)is 20 A.At this current,what is the drift velocity of the electrons? The number of electron carriers in 1.0 cm³ of copper is and e = 1.60 × 10^-19 C.

A platinum wire is used to determine the melting point of indium.The resistance of the platinum wire is 2.000 Ω at 20°C and increases to 3.072 Ω as the indium starts to melt.What is the melting point of indium? The temperature coefficient of resistivity for platinum is

The temperature coefficient of resistivity for copper is 0.0068 (C°)^-1.If a copper wire has a resistance of 104 Ω at 20°C,what is its resistance 80°C?

When a potential difference of 10 V is placed across a certain solid cylindrical resistor,the current through it is 2 A.If the diameter of this resistor is now tripled,the current will be

A silver wire with resistivity carries a current density of What is the magnitude of the electric field inside the wire?

A 110-V hair dryer is rated at 1200 W.What current will it draw when operating from a 110-V electrical outlet?

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?