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In the given circuit, the current flowing through the resistance 20 is 0.3 A, while the ammeter reads 0.9 A. The value of R1 is . [figure]
30
R1, 20 Ω and 15 Ω are in parallel (same p.d. V); the ammeter reads the total current.
V=0.3 20=6 V
I15= 615=0.4 A
IR1=0.9-(0.3+0.4)=0.2 A
R1= 60.2=30
Answer: 30
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