Need help finding value of R2
Voltage source 115, R1 and R2 are in parallel, R1 100Ω, R2 100mA, R3 is in series R3 150Ω. Should be easy but...

 

...But apart from the fact that we are not likely to supply direct answers for somebody's circuit theory homework, however basic, we are not mind-readers.

At the very least, post a schematic and explain your attempt to solve this. What is your difficulty with it?

 

R1 100Ω
+115v-- --R3 150Ω neg
R2 100mA
How do I calculate the resistance value of R2?

 

115vdc R1//R2 + R3.
R1=100ohm, R2=100mA, R3=150ohm
I will try type circuit here.
,,,,,,,,,,R1 100 ohm
+115v,,,,,,,,,,,,,,,,,,,,,,neg
,,,,,,,,,,R2 100 mA
I don't know how to get the ohm value for R2. The textbook isn't very clear. Thanks

 

Oops I forgot to put in R3
,,,,,,,,,,,,,,R1 100 ohm
+115v,,,,,,,,,,,,,,,,,,,,,,,,,,,,,R3 150 ohm
,,,,,,,,,,,,,,R2 100 mA

 

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Make a Thevenin equivalent for the two known resistors R1 and R3 and power supply from R2's point of view.

Solve for the voltage across R2 given the known 100mA current draw.