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(Electricity) How much resistance is going across R1?

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it-sall-in-th... | eNoter

Posted June 22, 2013 at 2:48 PM via web

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(Electricity)

How much resistance is going across R1?

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Mary Joy Ripalda | High School Teacher | (Level 3) Educator

Posted June 22, 2013 at 3:16 PM (Answer #1)

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To solve for the value of R, its voltage and current should be determine.

To do so, consider the two loads, R and L1.

Since they are in series, the current passing through L1 and R are the same.

So, use the voltage rating and power consumption of L1 to get `I_R` . 

`P=IV`

`0.5=I_(L1)*6`

`0.5/6=I_(L1)`

`0.0833=I_(L1)`

Since,

`I_(L1)=I_R`

then the current of R is:

`I_R=0.0833`

Furthermore, when the loads are in series, the sum of the voltage across each load is equal to voltage supply.

So the voltage across R is,

V_R+V_(L1)=9

V_R+6=9

V_R=9-6

V_R=3

Now that I_R and V_R are known, apply the formula of Ohm's Law to get its resistance.

`V=IR`

`V_R=I_R*R`

`3=0.0833*R`

`3/0.083=R`

`36=R`

Hence, the resistance of R is 36 ohms.

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