Question

Carefully study the circuit diagram in the figure and calculate the value of resistor x.

Answer 1

From Ohm's law,
V = IR
$6V=0.4A[R_1+R_2+R_3]$
$R_2=\{\frac{1}{12}+\frac{1}{6}+\frac{1}{3}\}\Omega =\frac{12}{7}\Omega$
$\Rightarrow 6V=0.4A[2\Omega +\frac{12}{7}\Omega +x\Omega ]$
$\Rightarrow 6V=0.8+\frac{4.8}{7}+0.4x$
$\Rightarrow 7\times 6=0.8\times 7+4.8+0.4\times 7x$
$\Rightarrow 42-10.4=2.8x\Rightarrow x=\frac{31.6}{2.8}=11.28\Omega$