(Electricity) How much resistance is going across R1?

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lemjay | High School Teacher | (Level 3) Senior Educator

Posted on

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` . 







then the current of R is:


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,





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






Hence, the resistance of R is 36 ohms.