Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
72 Cards in this Set
- Front
- Back
What is the rate at which charges move through a given area?
|
Electric Current
|
|
What does DC mean?
|
Direct Current: charges move in one direction only
|
|
What does AC mean?
|
Alternating current: motion of charges continuously changes in forwards & reverse
|
|
Who developed DC and AC?
|
Sr. William Thomson
|
|
What is the opposition to the flow of current in a conductor?
|
Resistance
|
|
How does resistance increase when the length of the conductor increases?
|
When length increases, more obstacles are in the way of the current- therefore- more resistance.
|
|
Why does the resistance decrease if the cross sectional area increases?
|
When area increases, less obstacles are in the way, there's more room and less resistance. <3
|
|
Increasing the length of a wire will ____ its resistance to current.
|
increase
|
|
A thicker wire will have ____ resistance than another wire of the same length, material and temp.
|
higher
|
|
Light bulbs are essentially resistors inside of a vacuum bulb. Why does the filament of a light bulb glow?
|
The PE(elec) of charges is converted to light/heat energy.
|
|
For a question that says: which of the following wires would have the LEAST resistance? and it gives you length & diameter, what would you do?
|
do length/diameter^2
|
|
For a question that says: which of the following wires would have the GREATEST resistance? and it gives you length and temp, what would you do?
|
find highest temp w/highest length
|
|
What are the units of resistance?
|
(ohms)(Ω)
|
|
What are the units of electric potential?
|
(volts)(v)
|
|
What are the units of Electric current?
|
(amps)(A)
|
|
What are the units of Electric Power?
|
(watts)(w)
|
|
What is the same in a series circuit?
|
current
|
|
What is the same in a parallel?
|
Voltage (p. difference)
|
|
4 bulbs illuminate a small gym. Wired that if one burns out, the others will stay lit. What types of connections will we see in this circuit?
|
Parallel
|
|
What does ΔQ represent?
|
amount of charge
|
|
I is the ratio of the ___ to the ___
|
charge to the time
|
|
What is the unit for I?
|
A (ampere, or amps)
|
|
What are the 2 sources of current?
|
batteries and generators
|
|
What does batteries do?
|
convert chemical energy into electrical energy
|
|
What do generators do?
|
convert mechanical energy into electrical energy
|
|
What are the 2 types of current?
|
Direct current and Alternating current
|
|
What is direct current?
|
charges move in one direction only
|
|
What is alternating current?
|
motion of charges continuously changes in forward & reverse directions
|
|
How many hertz in US and how many in Europe?
|
US: 60 hz
Europe: 50 hz |
|
What does A stand for?
|
cross-sectional area
|
|
What does a slanted P stand for?
|
resistivity of material (ohms)(meters)
|
|
What is Ohm's Law?
|
ΔV = IR
|
|
Who was Ohm's Law named after?
|
Georg Ohm
|
|
What does I stand for?
|
current
|
|
What are the 4 things resistance depends on?
|
length, cross-sectional area, material and temp
|
|
Increasing length of a conductor increase-
|
resistance
|
|
Decreasing area increases-
|
resistance
|
|
Atomic structure of different conductors may affect-
|
movement of charge
|
|
Temp increases, so the ___ increases
|
resistance
|
|
What is electric power?
|
The rate of conversion of electrical energy
|
|
What are superconductors?
|
Have no resistance below their critical temps
|
|
What are some examples of superconductors?
|
aluminum, tin, lead, zinc
|
|
What is the Meissner Effect?
|
superconductors repel magnets below the critical temp
|
|
What is the Meissner Effect used for?
|
high speed trains
|
|
What is a schematic diagram?
|
depicts the construction of an electrical circuit
|
|
What is a closed circuit?
|
a closed-loop path that e- can follow (lights on)
|
|
What is an open-circuit?
|
exists when there's no complete path, thus no flow of charge (no current-lights off)
|
|
Example of closed circuit?
|
lights on
|
|
Example of open circuit?
|
lights off
|
|
+-----II---------
|
single cell
|
|
+---IiIiIi-----
|
battery
|
|
-----------
|
connecting wire
|
|
______/\/\/\/------
|
resistor
|
|
_____/ ______
|
switch open
|
|
____i-i_____
|
stich closed
|
|
In a light bulb, the electrons leave the neg(-) terminal and travel through the--
|
connecting wire
|
|
In a light bulb, the PE elec of the charges is converted to
|
light/heat energy
|
|
Are electrons consumed in a lightbulb?
|
no!, but the energy they carry is transferred to other outlets via te loads of the circuit
|
|
what happens to voltage: lots of resistance?
|
voltage drops a lot
|
|
copper has a little bit of resistance, so what happens to voltage?
|
voltage resists change
|
|
What's the equation for resistors in a series?
|
R(eq) = R1 + R2 + R3...
|
|
What's the equation for resistors in parallel?
|
(reciprocal sum)
1/R(eq) = 1/R1 + 1/R2 + 1/R3... |
|
Series and Current?
|
Same
|
|
Parallel and Current?
|
Sum
|
|
Series and voltage?
|
sum
|
|
Parallel and voltage?
|
same
|
|
When parallel, voltage is?
|
same
|
|
When parallel, current is?
|
sum
|
|
When series, current is?
|
same
|
|
When series, voltage is?
|
sum
|
|
How to add equiv resistance in series?
|
add sum
|
|
How to add equiv resistance in parallel?
|
recip. sum
|