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Question:

The power dissipated in the circuit shown in the figure is 30 Watts. What is the value of R?

15Ω

30Ω

10Ω

20Ω

Solution:

P=V²/Req
30=(10)²/(5R/(R+5))
5R/(R+5)=100/30=10/3
15R=10R+50
5R=50
R=10Ω