Section Two Flashcards
What are the positive and negative terminals called?
Anode = positive
Cathode = negative
What is Vf
Forward Voltage
Voltage dropped across the led
How does an LED’s voltage drop work
If the Voltage drop is lower than what the led says it needs to be, the current is very small, but once the voltage drop gets to the forward voltage it opens and current can go through
What is If
Forward Current
Current passing through a component
What is the decimal form of 2mA?
.002
What are Kirchhoff’s Rules
Kirchhoff’s Current Law
Kirchhoff’s Voltage Law
What is Kirchhoff’s Current Law
The total current entering a node is exactly equal to the current leaving the node as it has no other place to go except to leave as no current is lost within the node
So the sum of all currents entering and leaving a node must be equal to zero
What is Kirchhoff’s Voltage Law
In any closed-loop network, the total voltage around the loop is equal to the sum of all voltage drops within the same loop
The algebraic sum of all voltages within the loop must be equal to zero
V - IR1 - IR2 - IR3 = 0
IR1(Voltage drop)
What does the symbol E mean?
Sigma = sum total
What’s the equation for voltage drop?
I * R
What is the Kirchhoff’s Voltage Law equation
V - IR1 - IR2 - IR3 = 0
IR1 = Voltage drop across R1
I = V/R1 + R2 + R3 = 2.00 A (Don’t know why he brought this up, but eh)
Tell How to use Kirchhoff’s Rules
Label the points in the circuit diagram using lowercase letters (a, b, c)
Locate nodes in circuits (nodes/junctions = points where 3 or more wires connect) Label each node with the currents and directions into and out of it.
Choose the loops in the circuit. Every component must be contained in at least one loop.
Apply Kirchhoff’s current law
Apply Kirchhoff’s Voltage Law
If direction of travel is the same as current flow, the voltage drop is a negative
If the direction of travel is opposite of current it’s positive
If from negative to positive on voltage you get a positive value
If from positive to negative you get a negative value
WHAT IS DIRECTION OF TRAVEL (From pos to neg of neg to pos)
Basically this looks like it’s saying if you follow conventional current as your direction to You get a positive number for your voltage drop and a negative for your voltage… because your voltage is dropping as it travels to the cathode
What are the 4 different equations for Kirchhoff’s rules?
This will all be based off of Point a to point b with a resistor in between:
a –ww–b
If direction == current direction, Voltage drop: Vb - Va = -IR (-IR just means you will have a negative value here since you’re going the right way, hence, you DROP voltage, for the opposite you’ll GAIN voltage)
if the direction == current direction (cathode to anode) you get a positive value:
Vb - Va = +E The opposite happens when you go the opposite way.
(This is for voltage)
You have two resistors in parallel and want to determine the voltage drop on each.
R1 is 500 and R2 is 1.5K
Vin is 5V
R1 / R1 + R2
for the next
R2 / R1 + r2
or you can get total amps and multiply each by that
In essence, what is the jist of Kirchhoff’s laws?
Kirchhoff’s Voltage Law - The sum of current entering a junction must be equal to the currents leaving a junction.
Kirchhoff’s Current Law - The sum of all voltage drops must equal 0
What is electrical power and what is the equation for it?
Electric power is measured by combining how much electrical energy is transferred and how fast that transfer happens
What is energy measured in
Joules
What is the equation for wattage?
W = Joules/seconds
What are Significant Figures?
You use these when determining how many decimal places you care to take from amps to put in an equation
Significant figures are just numbers that have meaning
2V would have 1 SF
12.4 Ohm would have 3
0.12 Would only have 2 since that one doesn’ t really mean anything
