Question 1

Which one of the following quantities is correctly matched to its unit?

Accepted Answer

A) power - kW·h 
B) energy - kW 
C) potential difference - J/C 
D) current - A/s 
E) resistance - V/C 
A) power - kW·h 
B) energy - kW 
C) potential difference - J/C 
D) current - A/s 
E) resistance - V/C C

Question 2

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:

Accepted Answer

A) 0.63 A 
B) 2.0 A 
C) 5.9 A 
D) 300 A 
E) 26000 A 
A) 0.63 A 
B) 2.0 A 
C) 5.9 A 
D) 300 A 
E) 26000 A B

Question 3

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:

Accepted Answer

A) 0.056 W 
B) 0.167 W 
C) 0.50 W 
D) 1.5 W 
E) none of these 
A) 0.056 W 
B) 0.167 W 
C) 0.50 W 
D) 1.5 W 
E) none of these A

Question 4

Suppose the electric company charges 10 cents per kW.h.How much does it cost to use a 125 watt lamp 4 hours a day for 30 days?

Accepted Answer

A) $1.20 
B) $1.50 
C) $1.80 
D) $7.20 
E) none of these 
A) $1.20 
B) $1.50 
C) $1.80 
D) $7.20 
E) none of these

Question 5

Current has units:

Accepted Answer

A) kilowatt·hour 
B) coulomb/second 
C) coulomb 
D) volt 
E) ohm 
A) kilowatt·hour 
B) coulomb/second 
C) coulomb 
D) volt 
E) ohm

Question 6

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 $\degree$C to 30 $\degree$C in about:

Accepted Answer

A) 12 s 
B) 50 s 
C) 3.5 min 
D) 15 min 
E) 45 min 
A) 12 s 
B) 50 s 
C) 3.5 min 
D) 15 min 
E) 45 min

Question 7

A certain wire has resistance R.Another wire, of the same material, has half the length and half the diameter of the first wire.The resistance of the second wire is:

Accepted Answer

A) R/4 
B) R/2 
C) R 
D) 2R 
E) 4R 
A) R/4 
B) R/2 
C) R 
D) 2R 
E) 4R

Question 8

A 60-watt light bulb carries a current of 0.5 ampere.The total charge passing through it in one hour is:

Accepted Answer

A) 3600 C 
B) 3000 C 
C) 2400 C 
D) 1800 C 
E) 120 C 
A) 3600 C 
B) 3000 C 
C) 2400 C 
D) 1800 C 
E) 120 C

Question 9

You wish to triple the rate of energy dissipation in a heating device.To do this you could triple:

Accepted Answer

A) the potential difference keeping the resistance the same 
B) the current keeping the resistance the same 
C) the resistance keeping the potential difference the same 
D) the resistance keeping the current the same 
E) both the potential difference and current 
A) the potential difference keeping the resistance the same 
B) the current keeping the resistance the same 
C) the resistance keeping the potential difference the same 
D) the resistance keeping the current the same 
E) both the potential difference and current

Question 10

It is better to send 10,000 kW of electric power long distances at 10,000 V rather than at 220 V because:

Accepted Answer

A) there is less heating in the transmission wires 
B) the resistance of the wires is less at high voltages 
C) more current is transmitted at high voltages 
D) the insulation is more effective at high voltages 
E) the iR drop along the wires is greater at high voltage 
A) there is less heating in the transmission wires 
B) the resistance of the wires is less at high voltages 
C) more current is transmitted at high voltages 
D) the insulation is more effective at high voltages 
E) the iR drop along the wires is greater at high voltage

Question 11

A certain x-ray tube requires a current of 7 mA at a voltage of 80 kV.The rate of energy dissipation is:

Accepted Answer

A) 5600 W 
B) 560 W 
C) 26 W 
D) 11.4 W 
E) 0.088 W 
A) 5600 W 
B) 560 W 
C) 26 W 
D) 11.4 W 
E) 0.088 W

Question 12

If the potential difference across a resistor is doubled:

Accepted Answer

A) only the current is doubled 
B) only the current is halved 
C) only the resistance is doubled 
D) only the resistance is halved 
E) both the current and resistance are doubled 
A) only the current is doubled 
B) only the current is halved 
C) only the resistance is doubled 
D) only the resistance is halved 
E) both the current and resistance are doubled

Question 13

A 10-ohm resistor has a constant current.If 1200 C of charge flow through it in 4 minutes what is the value of the current?

Accepted Answer

A) 3.0 A 
B) 5.0 A 
C) 20 A 
D) 120 A 
E) 300 A 
A) 3.0 A 
B) 5.0 A 
C) 20 A 
D) 120 A 
E) 300 A

Question 14

The rate at which electrical energy is used may be measured in:

Accepted Answer

A) watt/second 
B) watt·second 
C) watt 
D) joule·second 
E) kilowatt·hour 
A) watt/second 
B) watt·second 
C) watt 
D) joule·second 
E) kilowatt·hour

Question 15

Which of the following graphs best represents the current-voltage relationship of an incandescent light bulb?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 16

A current of 0.3 A passes through a lamp for 2 minutes using a 6 V power supply.The energy dissipated by this lamp during the 2 minutes is:

Accepted Answer

A) 1.8 J 
B) 12 J 
C) 20 J 
D) 36 J 
E) 216 J 
A) 1.8 J 
B) 12 J 
C) 20 J 
D) 36 J 
E) 216 J

Question 17

Current is a measure of:

Accepted Answer

A) force that moves a charge past a point 
B) resistance to the movement of a charge past a point 
C) energy used to move a charge past a point 
D) amount of charge that moves past a point per unit time 
E) speed with which a charge moves past a point 
A) force that moves a charge past a point 
B) resistance to the movement of a charge past a point 
C) energy used to move a charge past a point 
D) amount of charge that moves past a point per unit time 
E) speed with which a charge moves past a point

Question 18

Of the following the copper conductor that has the least resistance is:

Accepted Answer

A) thin, long and hot 
B) thick, short and cool 
C) thick, long and hot 
D) thin, short and cool 
E) thin, short and hot 
A) thin, long and hot 
B) thick, short and cool 
C) thick, long and hot 
D) thin, short and cool 
E) thin, short and hot

Question 19

An incandescent light bulb is marked "60 watt, 120 volt".Its resistance is:

Accepted Answer

A) 0.5 $\Omega$ 
B) 120 $\Omega$ 
C) 180 $\Omega$ 
D) 240 $\Omega$ 
E) 300 $\Omega$ 
A) 0.5 $\Omega$ 
B) 120 $\Omega$ 
C) 180 $\Omega$ 
D) 240 $\Omega$ 
E) 300 $\Omega$

Question 20

A certain sample carries a current of 4 A when the potential difference is 2 V and a current of 10 A when the potential difference is 4 V.This sample:

Accepted Answer

A) obeys Ohm's law 
B) has a resistance of 0.5 $\Omega$ at 2 V 
C) has a resistance of 2 $\Omega$ at 2 V 
D) has a resistance of 25 $\Omega$ at 2 V 
E) does not have a resistance 
A) obeys Ohm's law 
B) has a resistance of 0.5 $\Omega$ at 2 V 
C) has a resistance of 2 $\Omega$ at 2 V 
D) has a resistance of 25 $\Omega$ at 2 V 
E) does not have a resistance

Exam 26: Current and Resistance

Which one of the following quantities is correctly matched to its unit?

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:

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:

Suppose the electric company charges 10 cents per kW.h.How much does it cost to use a 125 watt lamp 4 hours a day for 30 days?

Current has units:

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 °\degree° C to 30 °\degree° C in about:

A certain wire has resistance R.Another wire, of the same material, has half the length and half the diameter of the first wire.The resistance of the second wire is:

A 60-watt light bulb carries a current of 0.5 ampere.The total charge passing through it in one hour is:

You wish to triple the rate of energy dissipation in a heating device.To do this you could triple:

It is better to send 10,000 kW of electric power long distances at 10,000 V rather than at 220 V because:

A certain x-ray tube requires a current of 7 mA at a voltage of 80 kV.The rate of energy dissipation is:

If the potential difference across a resistor is doubled:

A 10-ohm resistor has a constant current.If 1200 C of charge flow through it in 4 minutes what is the value of the current?

The rate at which electrical energy is used may be measured in:

Which of the following graphs best represents the current-voltage relationship of an incandescent light bulb?

A current of 0.3 A passes through a lamp for 2 minutes using a 6 V power supply.The energy dissipated by this lamp during the 2 minutes is:

Current is a measure of:

Of the following the copper conductor that has the least resistance is:

An incandescent light bulb is marked "60 watt, 120 volt".Its resistance is:

A certain sample carries a current of 4 A when the potential difference is 2 V and a current of 10 A when the potential difference is 4 V.This sample:

Measurement

Motion Along a Straight Line

Vector

Motion in Two and Three Dimensions

Force and Motion I

Force and Motion II

Kinetic Energy and Work

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

Gravitation

Fluids

Oscillations

Waves I

Waves II

Temperature, Heat, and the First Law of Thermodynamics

The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Electric Charge

Electric Fields

Gauss Law

Electric Potential

Capacitance

Circuits

Magnetic Fields

Magnetic Fields Due to Currents

Induction and Inductance

Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

Electromagnetic Waves

Images

Interference

Diffraction

Relativity

Photons and Matter Waves

More About Matter Waves

All About Atoms

Conduction of Electricity in Solids

Nuclear Physics

Energy From the Nucleus

Quarks, Leptons, and the Big Bang

Filters

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 *10⁷A/m².The current is:

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 $\degree$ C to 30 $\degree$ C in about: