physics chapter 34 and 35
when plugged into a 120-V wall outlet, how much current is used by a toaster rated at 1200 W?
10 A
the current through a 10-ohm resistor connected to a 120-V power supply is___
12 a
power outlets in our homes typically have a potential difference of____
120 V
how much power is used by a 6.0-V flashlight battery that draws .5A of current?
3 W
an electric heater is rated at 300 W for use in a 110-V circuit. The safety fuse in the circuit can handle 15A of current. How many heaters can be safely operated in the circuit?
5
when a 10-v battery is connected to a resistor, 2 A of current flows in the resistor. What is the resistor's value?
5 ohms
a 10-ohm resistor has a 5-a current in it. what is the voltage across the resistor?
50 or 15
the frequency of AC current in North america is___
60 hertz
a light bulb is plugged into a 120- volt outlet and has an .8 A current in it. what is the power rating of the light bulb?
96 W
current from a battery is always____?
DC
when one light bulb in a series circuit containing several high bulbs burns out_____
all of the other light bulbs go out
in order to form an electrical circuit, you ned to have____
all the above: a power source, a light bulb or some resistance, wires or conductors to connect everything, a complete path for the current
electrical resistance in a wire depends on the wire's ____
all the above: conductivity, length, thickness, temperature
an example of a voltage source is____
all the above: dry cell, flashlight battery, car battery, and a generator
fuses and circuit breakers are used to _____
all the above: protect us, prevent overloading, break the circuit when too much current is being used, and keep wires from getting overheated
closed circuit is a circuit in which____
charge can flow
electric power is defined as____
current times voltage
when we say an appliance such as a toaster uses up electricity, we really are saying that____
electron kinetic energy is changed into heat
compared to the filament thickness on a 60-w light bulb, the filament thickness of a 100-w light bulb will be___
greater
an open in a series circuit
happens for all the above
for most conductor, as their temp increases, their resistance ____
increases
what is the purpose of the third prong in an appliance plug?
it prevents charge from building on an appliance by grounding it
when resistors are put in series next to each other, the total resistance is____
larger than that of any individual resistor
compared to thin wires, electrical resistance in thick wires is____
less
compared to the resistance of two resistors connected in series, the same two resistors connected in parallel have____
less resistance
it was discovered that the current to a circuit is directly proportional to the voltage and inversely proportional to the resistance. This is____
ohm's law
electrical resistance is measured in____
ohms
electrical elements in our homes are connected in____
parallel
in an alternating current circuit, electrons flow is___
simply back and forth
when resistors are put in parallel with each other their total resistance is _____
smaller than the resistance of any one of the resistors
where do the electrons come from that produce heat and light in a light bulb?
the bulbs wire filament
electric current is____
the flow of electric charge
when one light bulb in a parallel circuit containing several light bulbs burns out, ____
the other bulb continues burning
when a light switch in a DC circuit is turned on, the average net speed of electrons in the lamp is____
the speed of sound waves in metal
the primary reason a bird can perch harmlessly on bare high voltage wires is that____
there is no potential difference across the bird's feet
if u plug an electric toaster rated at 110 V into a 220- V outlet, current in the toaster will be _____
twice what it should be
an ampere is a____
unit of current
in a simple parallel circuit____
voltage across each branch is always the same
a short circuit occurs when?
wires in a circuit touch by passing circuit components
the symbol used to represent resistance in a schematic diagram is____
zigzag line