7/21/2019 EEE121 Lecture 10 (1)

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Previous Lecture Parallel Circuits

• Resistors in Parallel

• Voltage in a Parallel Circuit

• Kirchhof's Current Law

•  Total Parallel Resistance

• Application o Ohm's Law

• Current Sources in Parallel

• Current Dii!ers• Power in Parallel Circuits

• Parallel Circuit Applications

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Problems Solving_ParallelCircuits

Problem related to Resistors inParallel

"#$ Show how to connect the resistors in the

ollowing %igure in parallel across the &atter#

Lecture

10

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Problem related to Voltage ina Parallel Circuit

"#$ (hat is the oltage across an! the currentthrough each parallel resistor i the total oltageis $) V an! the total resistance is **+,- Thereare our resistors. all o e/ual alue#

)$#0 mA. *#1* mA. )#)+K

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Problems related to Kirchhof'sCurrent Law

"#$ There is a total o *++ mA o current into 2eparallel resistors# The currents through our o theresistors are *+ mA. $*+ mA. )* mA. an! $++ mA#(hat is the current through the 2th resistor-

$3* mA

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"#) 4n the circuit o ollowing %igure. !etermine theresistance R) .R5 . an! R1 #

13 mV. )) 6. $++ 6. $#1) mA. 5

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"#5 The electrical circuit in a room has a ceilinglamp that !raws $#)* A an! our wall outlets# Twota&le lamps that each !raw +#055 A are plugge!into two outlets. an! an electric heater that !raws

$OA is connecte! to the thir! outlet# (hen all othese items are in use. how much current is in themain line sering the room- 4 the main line isprotecte! & a $* A circuit &rea7er. how much

current can &e !rawn rom the ourth outlet-Draw a schematic o this wiring#

$)#8) A. )#+0

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"#1 The total resistance o a parallel circuit is)*,# (hat is the current through a ))+, resistorthat ma7es up part o the parallel circuit i the totalcurrent is $++ mA-

)#* V. $$#1 m

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Problems related to TotalParallel Resistance

"#$ (hat is the total resistance o twele 9#07,resistors in parallel-

*93 6

! ! i th ll i %i th ll i

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an! groun! in the ollowing %igure or the ollowingcon!itions-:a; S(4 an! S() open :&; S(4 close!# S()open

:c; S(4 open. S() close! :!; S(4 an! S()close!

*$+ 76. )1* 76. *$+ 76. $85

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Problems related toAlication o! "hm's Law

"#$ %our e/ual<alue resistors are connecte! inparallel# %ie olts are applie! across the parallelcircuit. an! $#$$ mA are measure! rom thesource# (hat is the alue o each resistor-

1#* 76. $0 7

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"#) %in! the alues o the unspeci2e! la&ele!/uantities in the ollowing circuit#

*+ mA. $++ 6. )++

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"#5 %in! the alues o the unspeci2e! la&ele!/uantities in the ollowing circuit#

45=$++ mA. 4)=$13 mA.4$=)*5 mA. R$=58*

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"#1 To what minimum alue can the $++,rheostat in the ollowing %igure &e a!>uste! &eorethe +#* A use &lows-

4$=#))A. 4)=#)0A. R)= *5#

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"#* %in! the alues o the unspeci2e! /uantitiesin the ollowing %igure#

45=05#5 mA. 4)=$99#3 mA. 4 T=5++ mA. R$=) 76. R)=

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Problem related to CurrentSources in Parallel

"#$ Determine the current through RL in each

circuit in the ollowing %igure#

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Problems related to Current#ividers

"#$ Determine the current in each &ranch o thecurrent !ii!ers o ollowing %igure#

9#00 ?A. 5#$) ?A *)* 6. *#)* mA. )#58 mA. $#*8 mA. +#3

" ) (hat is the current through each resistor in

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"#) (hat is the current through each resistor inthe ollowing %igure- R is the lowest<alue resistoran! all others are multiples o that alue asin!icate!#

+#10R, 1#0 mA. )#1 mA. $#*8 mA. $#)

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"#5 Determine all o the resistor alues in theollowing %igure# RT = 335,#

335 6. )#$1 mA. 5#5 76. $#0 76. *#9 76. 5#

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Problems related to Power inParallel Circuits

"#$ %in! the alues o the unspeci2e! /uantities inthe ollowing %igure#

P$=$#)* (. Vs=$+ V. 4)= 3* mA. R)= $55 6. 4$=$)* mA.R$=

i t Th t t l i t i $ + 7, ! th t t l

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 resistors# The total resistance is $#+ 7,. an! the totalcurrent is *+ mA# 4 each resistor is operating at one<halits maimum power leel. !etermine the ollowingB:a; The num&er o resistors :&; The alue o

each resistor:c; The current in each &ranch :!; The applie!oltage

•  

:a;) * ( $+ :&; $+ 76 :c;* mA :!;*