Chapter 7 HW
The current through a 10-ohm resistor connected to a 120-V power supply is
12 A
The amount of energy given to each coulomb of charge flowing through a 12-V battery is
12 J
A power line with a resistance of 2 ohms draws a current of 80 A. The power dissipated in the line is
12,800 W
Two charges separated by 1 m exert a 1.0-N force on each other. If the charges are pushed to 0.25-m separation, the force on each charge will be
16 N
A pair of 1-ohm resistors connected in parallel has a combined resistance of
2 ohms
The current through two identical light bulbs connected in series is 0.25 A. The voltage across both bulbs is 110 V. The resistance of a single light bulb is
220 ohms
A length of wire has resistance R. The same wire twice as long has resistance
2R
The power dissipated in a 4-ohm resistor carrying 3 A is
36 W
A resistor carries a current of 2 A when connected to a 10-V battery. What is the resistor's value?
5 ohms
Electrons flow in a wire when there is
A potential difference across its ends
When you purchase a water pipe in a hardware store, water is not included. When you purchase copper wire, electrons
Already exists in the wire
The electric charge on all electrons
Are identical
An electron and a proton
Attract each other
To say that electric charge is conserved is to say that electric charge
Can neither be created nor destroyed
The electric field in the wires of an ac circuit
Changes direction with time
The electric force between charges is strongest when the charges are
Close together
An ampere is a unit of electric
Current
A balloon will stick to a wooden wall if the balloon is charged
Either (positive and negative)
Which force binds atoms together to form molecules?
Electric
A positive ion has a deficiency of
Electrons
The number of protons in the nucleus of an electrically neutral atom is equal to the number of
Electrons that surround the nucleus
Two charged particles repel each other with a force F. If the charge on one particle is doubled and the distance between them is doubled, the force will be
F/2
Just as water flows from high to low pressure, electric charge flows from
High to low voltage
As more lamps are put into a parallel circuit, the overall current in the power source
Increases
Heat a copper wire and its electric resistance
Increases
Electric potential is measured in units of
Joules
The electric force between charges depends on the
Magnitude of electric charges and separation distance between electric charges (BOTH)
When two lamps are connected in series to a battery, the electric resistance that the battery senses is
More than the resistance of either lamp
A difference between an insulator and a conductor is that a conductor has more A) electrons than protons. B) protons than electrons. C) energy than an insulator. D) faster moving molecules. E) None of the above
None of the above
The electric field around an isolated electron has a certain strength 1 cm from the electron. The electric field strength 2 cm from the electron is A) half as much. B) the same. C) twice as much. D) four times as much. E) none of the above
None of the above
The headlights, radio, and defroster fan in an automobile are connected in
Parallel
As you comb your hair, electrons are rubbed onto the comb, which becomes
Positively
When you remove electrons from a metal cup, the cup becomes
Positively Charged
A negatively charged rod is brought near a metal can that rests on a wood table. You touch the opposite side of the can momentarily with your finger. The can then becomes
Positively charged
A difference between electric and gravitational forces is that electric forces include
Repulsive interactions
Two charged particles near each other are released. As they move, the force on each particle increases. Therefore, the particles have
The opposite sign