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Exam 17: Current and Resistance

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Question 41

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A wire carries a steady current of 0.1 A over a period of 20 s.What total charge passes through the wire in this time interval?

A) 200 C
B) 20 C
C) 2 C
D) 0.005 C

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Question 42

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Which process will double the power given off by a resistor?

A) doubling the current while doubling the resistance
B) doubling the current by making a resistance half as big
C) doubling the current by doubling the voltage
D) doubling the current while making the voltage half as big

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Question 43

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A solar panel measures 80 cm ´ 50 cm.In direct sunlight,the panel delivers 3.2 A at 15 V.If the intensity of sunlight is 1 000 W/m²,what is the efficiency of the solar panel in converting solar energy into electrical energy?

A wire has resistance R.A second wire has twice the length,twice the diameter,and twice the resistivity of the first wire.What is its resistance?

A light bulb has resistance of 240 W when operating at 120 V.Find the current in the light bulb.

If a 500-W heater carries a current of 4.00 A,what is the resistance of the heating element?

When a superconductor's temperature drops below the critical temperature,its resistance:

By what factor is the resistance of a copper wire changed when its temperature is increased from 20 $\degree$ C to 120 $\degree$ C? The temperature coefficient of resistivity for copper = 3.9 x 10^-3 ( $\degree$ C) ^-1.

Two cylindrical resistors are made of the same material and have the same resistance.The resistors,R₁ and R₂,have different radii,r₁ and r₂,and different lengths,L₁ and L₂.Which of the following relative values for radii and lengths would result in equal resistances?

A high-voltage transmission line carries 1 000 A at 700 kV for a distance of 100 miles.If the resistance in the wire is 1 W/mile,what is the power loss due to resistive losses?

Which is a unit of power?

An 8.00-W resistor is dissipating 100 watts.What are the current through it and the difference of potential across it?

An electric car is designed to run off a bank of 12-V batteries with total energy storage of 3.0 ´ 10⁷ J.If the electric motor draws 6 000 W in moving the car at a steady speed of 10 m/s,how far will the car go before it is "out of juice?"

A certain material is in a room at 27 $\degree$ C.If the absolute temperature (K) of the material is tripled,its resistance doubles.(Water freezes at 273 K. ) What is the value for a,the temperature coefficient of resistivity?

Ten coulombs of charge start from the negative terminal of a battery,flow through the battery and then leave the positive terminal through a wire,flow through a resistor and then return to the starting point on this closed circuit.In this complete process,the ten coulombs:

The size of the electric current in a electrical conductor is a function of which of the following?

A metal wire has a resistance of 10.00 W at a temperature of 20 $\degree$ C.If the same wire has a resistance of 10.55 W at 90 $\degree$ C,what is the resistance when its temperature is -20 $\degree$ C?

A Nichrome wire has a radius of 0.50 mm and a resistivity of 1.5 x 10^-6 W*m.If the wire carries a current of 0.50 A,what is the potential difference per unit length along this wire?

Materials having resistance changes as voltage or current varies are called: