470 220 Gnd5V Currents Through Parallel Resistors 1 living with the lab © 2011 LWTL faculty team.
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Transcript of 470 220 Gnd5V Currents Through Parallel Resistors 1 living with the lab © 2011 LWTL faculty team.
470W
220W
Gnd5V
Currents Through Parallel Resistors
1
living with the lab
© 2011 LWTL faculty team
Select Resistors Find the 220W and the 470W resistors from your parts kit.
Now, find the 220W resistor.
Example: 470 W resistor
4 = yellow7 = violetAdd 1 zero to 47 to make 470, so 1 = brown
So, 470 = yellow, violet, brown
color digit
black 0
brown 1
red 2
orange 3
yellow 4
green 5
blue 6
violet 7
gray 8
white 9
firstdigit
seconddigit
numberof zeros
tolerancegold = ±5%
silver = ±20%
2
living with the lab
build the parallel circuit belowmeasure the total current from the power source
Compute the current after you make your measurement.
curre
nt flo
w
current flow
Vo=5V
470W
220W
+ -
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+
+
currentmeasurement
3
living with the lab
𝑅𝑒𝑞=1
1220Ω
+1
470Ω
=149.9Ω𝑉=𝐼 ∙𝑅𝑜𝑟 𝐼=𝑉𝑅
𝐼=𝑉𝑅𝑒𝑞
=¿
use Ohm’s law:
5𝑉149.9Ω
=0.033 𝐴compare
Compute the current after you make your measurement.
current flow
Vo=5V
470W
220W
+ -
-
-
+
+
currentmeasurement
4
living with the lab
modify the parallel circuit as showmeasure the total current through the 220Ω resistor
𝑉=𝐼 ∙𝑅𝑜𝑟 𝐼=𝑉𝑅=¿
use Ohm’s law:5𝑉220Ω
=0.023 𝐴 compare
Compute the current after you make your measurement.
Vo=5V
470W
220W
+ -
-
-
+
+
currentmeasurement
5
living with the lab
modify the parallel circuit as showmeasure the current through the 470Ω resistor
𝑉=𝐼 ∙𝑅𝑜𝑟 𝐼=𝑉𝑅=¿5𝑉470Ω
=0.011 𝐴compare
use Ohm’s law:
~~
I = 22.7 mA
I =
10.7
mA
more current goes through smaller resistor
I =
33 m
A
Vo=5V
470W
220W
+ -
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+
+
6
living with the lab
check for conservation of charge
Kirchoff’s Current Law (KCL)The algebraic sum of currents entering a node is zero.
Current In = Current Out