In order for there to be a flow of charge from one place to another, there must be a
conductor such as a wire, connecting the two places,
Potential difference between the two places
An ampere is a
unit of charge
An example of a voltage source is
a dry cell, a generator, car battery, rubbing a rubber rod with fur
Electrical resistance in a wire depends on the wire's
conductivity, thickness, lenght
For most conductors, as their temperatures increase, their resistance
increases
A wire carrying a current is normally charged
not at all
A primary reason a bird can perch harmlessly on a bare high voltage wires is that
there is no potential difference across the bird's feet
Alternating current is made by
alternating the direction of voltage of the power source
Current from a batter is always
DC
In 2004, the number of electrons delivered to an average American home by an average power utility was
Zero
When we say an appliance uses up electricity, we really are saying that
electrons kinetic energy is changed into heat and other forms of energy
Electric power is defined as
current time voltage
Compared to the filament thickness on a 60 W light bulb, the filament thickness of a 100 W light bulb will be
greater
Power outlets in our homes typically have a potential difference of
120 V
When an 8 V battery is connected to a resistor, 2A of current flows in the resistor. What is the resistor's value?
4 ohms
The current through a 5 ohm resistor connected to a 150 V power supply is
30 A
A 15 ohm resistor has a 5 A current in it. What is the voltage across the resistor
more than 25 V
How much power is used by a 12 V car batter that draws .5 A of current
6 W
A 60 W light bulb and a 00-W light bulb are both rated at 12o V outlet. .which light bulb has more current in it
the 100 W bulb
IN order for current to flow in a circuit you must have
a complete path for the current
Electrical resistance is measured in
none of the above
When two light bulbs are connected in series, the
same amount of current always flows through each bulb
The symbol used to represent resistance in a schematic diagram is a
zigzag line
When restores are put in serious next to each other, their overall resistance is
larger than the resistance of any individual resistor
When resistors are put parallel with each other their overall resistance is
smaller than the resistance of any of the resitors
As more lamps are put into a series circuit, the overall current in the circuit
decreases
As more lamps are put into a series circuit, the overall current in the circuit
increases
When one light bulb in a series circuit containing several light bulbs burns out
none of the other light bulbs will light up
When one light bulb in a parallel circuit containing several light bulb burn out, the other light bulbs
burn the same as before
In a simple parallel circuit
current through each resistor is inversely proportional to the resistance
Two lamps, one with a thick filament and one with a thin filament, are connected in series. The current is greater in the lamp with the
current is the same in each lamp
Two lamps, one with thick filament and on with thin filament, are connected in parallel to a batter. The current is larger in the lamp with the
thick filament
Two lamps one with a thick filament and one with a thin filament, are connected in series to a battery. The voltage is greater across the lamp with the
thick filament
Two lamps, one with a thick filament and one with a thin filament, are connected in series to a battery. The voltage is greater across the lamp with the
Thin filament
The total resistance of a 10 ohm resistor and a 7 ohm resistor in series is
17 ohms
the total resistance of a 6 ohm resistor and a 12 ohm resistor in parallel is
4 ohms
charge flows from low potential to high potential
false
In solid conductors, positive current is the flow of portions in the conductor
false
Most of the electricity we buy though power companies is direct current
flase
When you turn on a light, electrons move at speed near the speed of light in order to light up the light bulb
false
The kilowatt hour is a unit of power used by power companies
false
Charge will move in a conductor when there is a difference in potential between the ends of the conductor
True
The unit of electric current is the ampere
true
In order to make a flashlight bulb light up. all you need to do is to run a wire from the positive terminal of a flashlight battery to the center of the bulb's base
False
In a series circuit, the total voltage drop across a series of resistors is the sum of voltage drops across each individual resistor
true
In a parallel circuit, current in each branch is the same
false
A schematic diagram is simplified, blocked out picture of a circuit in which parts of the circuit are represented by symbols
false
When connected in series, an electric circuit provides branched paths for the flow of electrons
false
A battery does 18 J of work on 10 coulombs of charge. What voltage does the batter supply
1.8 W
What is the current in a 60 w bulb connected to a 120 V source
.5 A
What is the power dissipated by a toaster that has a resistance of 40 ohms and is plugged into a 120 V outlet
360 W
How many 6 ohms resistors must be connected in parallel to create an equivalent resistance of 1 ohm
6
What is the equivalent resistance of a 30 ohm and a 20 ohm resistor connected in parallel
12 ohm
two identical resistors in parallel have an equivalent resistance of 7 ohms. If the same resistors were instead connected in series, what would be the equivalent resistance
28 ohms
A 30 V potential difference is applied across a series combination of an 8 ohm resistor and a 3 ohm resistor. What is the current in the 8 ohm resistor
2.7 A
A 20 V potential difference is applied across a parallel combination of a 60 ohm and a 10 ohm resistor. What is the current in the 10 ohm resistor
2 A
A 20 ohm resistor is connected in series with a 20 V battery and a three branch parallel network with branches whose resistances are 6 ohms each. Ignoring the battery's internal resistance, what is the current in the battery
5 A