Question

In the circuit shown the variable resistance is so adjusted that the ammeter reading is same in both the position 1 and 2 of the key. The reading of ammeter is $2A$. If $E=10V$, then $x$ is

• A. $2\Omega$
• B. $5\Omega$
• C. $10\Omega$
• D. $20\Omega$

Answer 1

The correct option is B $5\Omega$

Since reading of ammeter is 2A, the current through wire 1 is 2A.

Same must be the current through wire 2.

Applying Kirchoff's Voltage Law through the loop containing both positions of key.

$E-\left(I\right)\left(x\right)=0$

$⟹x=\frac{E}{2A}=5\Omega$