Answer:
12 Ω
Step-by-step explanation:
Data obtained from the question include:
Resistor 1 (R1) = 50 Ω.
Resistor 2 (R1) = 30 Ω.
Resistor 3 (R3) = 20 Ω.
Resistor 4 (R4) = R
Galvanometer reading = Zero deflection.
The Resistor 4 (R4) in the Wheatstone bridge can be obtained as follow:
Since the galvanometer gives zero deflection, it means the bridge is balanced. Therefore,
R1/R2 = R3/R4
50/30 = 20/R
Cross multiply
50 x R = 30 x 20
Divide both side by 50
R = (30 x 20)/50
R = 12 Ω
Therefore, the value of R in the wheatstone bridge is 12 Ω.