A wire with a length of 150 m and a radius of 0.15 mm carries a current with a uniform current density of 2.8×107 A/m2. The current is: 0.63 A 2.0 A 5.9 A 300 A 26000 A
A wire is 1 m long and 1×10−6 m2 in cross-sectional area. When connected to a potential difference of 2 V, a current of 4 A exists in the wire. The resistivity of this wire is: 2×10−6 Ω⋅m 8×10−6 Ω⋅m 1×10−7 Ω⋅m 4×10−7 Ω⋅m 5×10−7 Ω⋅m
Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1 m. Conductor B is a hollow tube of inside diameter 1 m and outside diameter 2 m. The ratio of their resistance, RA/RB, is: 1 2 2 3 4
A certain resistor dissipates 0.5 W when connected to a 3 V potential difference. When connected to a 1 V potential difference, this resistor will dissipate: 0.056 W 0.167 W 0.50 W 1.5 W none of these
The mechanical equivalent of heat is 1 cal = 4.18 J. The specific heat of water is 1 cal/g⋅K, and its mass is 1 g/cm3. An electric immersion water heater, rated at 400 W, should heat a liter of water from 10∘C to 30∘C in about: 12 s 50 s 3.5 min 15 min 45 min
How long (hours) do electrons take to move through a cable of length 9.40 m? There are 8.49×1028 conduction electrons per cubic meter. The current is 30.0 A. The cross-sectional area is 2.50×10−5 m2.4.32 8.87 67.9 9.49 12.3 161 51.5 107 29.6 79.8
Nine identical wires, each of diameter d and length L, are connected in series. The combination has the same resistance as a single similar wire of length L but whose diameter is: 9 d 3 d d/3 d/9 d/81
Resistances of 2.0 Ω, 4.0 Ω, and 6.0 Ω and a 24−V emf device are all in series. The potential difference across the 2.0−Ω resistor is: 4 V 8 V 12 V 24 V 48 V
A battery of emf 24 V is connected to a 6.0−Ω resistor. As a result, current of 3.0 A exists in the resistor. The rate at which energy is being dissipated in the battery is: 3.0 W 6.0 W 18 W 54 W 72 W
A total resistance of 3.0 Ω is to be produced by combining an unknown resistor R with a 12 Ω resistor. What is the value of R and how is it to be connected to the 12 Ω resistor? 2.4 Ω, parallel 2.4 Ω, series 4.0 Ω, parallel 4.0 Ω, series 9.0 Ω, series
By using only two resistors, R1 and R2 a student is able to obtain resistances of 3 Ω, 4 Ω, 12 Ω, and 16 Ω. The values of R1 and R2 are: 3 Ω, 4 Ω 2 Ω, 12 Ω 3 Ω, 16 Ω 4 Ω, 12 Ω 4 Ω, 16 Ω
A certain voltmeter has an internal resistance of 10, 000 Ω and a range from 0 to 100 V. To give it a range from 0 to 1000 V, one should connect: 100, 000 Ω in series 100, 000 Ω in parallel 1000 Ω in series 1000 Ω in parallel 90, 000 Ω in series
A 60-watt light bulb carries a current of 0.5 ampere. The total charge passing through it in one hour is: 3600 C 3000 C 2400 C 1800 C 120 C
Copper contains 8.4×1028 free electrons per cubic meter. A copper wire of cross-sectional area 7.4×10−7 m2 carries a current of 1 A. The electron drift speed is approximately: 3×108 m/s 103 m/s 1 m/s 10−4 m/s 10−23 m/s
The magnitude J of the current density in a certain wire with a circular cross section of radius R = 2.27 mm is given by J = (3.18 × 108)r2, with J in amperes per square meter and radial distance r in meters. What is the current through the outer section bounded by r = 0.911R and r = R? Number Units
When 153 V is applied across a wire that is 11 m long and has a 0.31 mm radius, the magnitude of the current density is 2.0 × 104 A/m2. Find the resistivity of the wire. Number Units
A block in the shape of a rectangular solid has a cross-sectional area of 4.65 cm2 across its width, a front-to-rear length of 22.6 cm, and a resistance of 1230 Ω. The block's material contains 6.93×1022 conduction electrons/m3. A potential difference of 49.9 V is maintained between its front and rear faces. (a) What is the current in the block? (b) If the current density is uniform, what is its magnitude? What are (c) the drift velocity of the conduction electrons and (d) the magnitude of the electric field in the block? (a) Number Units (b) Number Units (c) Number Units (d) Number Units