Question

In above circuit if current through $10 \,\Omega$ resistor is $2.5\, A$, value of $R$ is _______.

• A. $50\, \Omega$
• B. $40 \,\Omega$
• C. $8 \,\Omega$
• D. $10 \,\Omega$

Answer 1

Answer: (C)

$i_{1}=2.5 A $
so $ i=i_{1}+i_{2}$
So voltage across $10\, \Omega=i \times R=25$
Voltage across $40 \,\Omega=10 \times 2 .=25\, V$
$R=\frac{25}{i_{1}+i_{2}}$
$i_{2}=\frac{25}{40} A$
$\therefore R=8\, \Omega$