Exam 17: Current and Resistance

A resistor is made of a material that has a resistivity that is proportional to the current going through it.If the voltage across the resistor is doubled,what happens to the current through it?

A flashlight bulb operating at a voltage of 5.0 V has a resistance of 7.0 Ω.How many electrons pass through the bulb filament per second (e = 1.6 × 10−¹⁹ C)?

Suppose that a voltage surge produces 140 V for a moment in a 115-V line.What will temporarily be the output of a 100-W light bulb assuming its resistance does not change?

A metallic conductor has a resistivity of 35 × 10−⁶ Ω⋅m.What is the resistance of a piece that is 20 m long and has a uniform cross-sectional area of 4.0 × 10−⁶ m²?

The quantity volt is equivalent to which of the following?

When you flip a switch to turn on a light,the delay before the light turns on is determined by:

A superconducting wire's chief characteristic is which of the following?

The heating coil of a hot water heater has a resistance of 17 Ω and operates at 300 V.How long a time is required to raise the temperature of 115 kg of water from 18°C to 75°C? (The specific heat for water = 10³ cal/kg⋅°C and 1.0 cal = 4.186 J).

The unit of electric resistance,the ohm,is equivalent to which of the following?

Three resistors,each of different value,are used in a circuit with a power source supplying 12 volts.For which of the following resistor combinations is the total power supplied the greatest?

The resistance of a platinum wire is to be calibrated for low-temperature work.A platinum wire with resistance 1.5 Ω at 30°C is immersed in liquid nitrogen at 93 K (−180°C).If the temperature response of the platinum wire is linear,what is the expected resistance of the platinum wire at −180°C? [α_platinum = 3.92 × 10−³ (°C)−¹].

​If the current carried by a conductor is increased by a factor of 2,what happens to the electron drift velocity.

If a lamp has a resistance of 265 Ω when it operates at 250 W,what current does it carry?

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

The unit for rate of energy transformation,the watt,in an electric circuit is equivalent to which of the following?

A certain material is in a room at 25°C.If the absolute temperature (K)of the material is tripled,its resistance doubles.(Water freezes at 273 K. )What is the value for α,the temperature coefficient of resistivity?

Some superconductors are capable of carrying a very large quantity of current.If the measured current is 3.00 × 10⁶ A,how many electrons are moving through the superconductor per second? (e = 1.60 × 10−¹⁹ C)

If the current in a wire is tripled,what effect does this have on the electron drift velocity in the wire?

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

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