In the given circuit, the current flowing through the resistance $$20 \;\Omega$$ is $$0.3$$ A, while the ammeter reads $$0.9$$ A. The value of $$R_1$$ is ______ $$\Omega$$.

all three resistors (R₁, 20 Ω, 15 Ω) are in parallel between the same two nodes

so total current = sum of branch currents

given:
current through 20 Ω = 0.3 A
total current = 0.9 A

so current through the other two branches:

I₁ + I₃ = 0.9 − 0.3 = 0.6 A

step 1: find voltage across network

V = I × R = 0.3 × 20 = 6 V

step 2: current through 15 Ω

I₃ = 6 / 15 = 0.4 A

step 3: current through R₁

I₁ = 0.6 − 0.4 = 0.2 A

step 4: find R₁

R₁ = V / I₁ = 6 / 0.2 = 30 Ω