question_answer

In the circuit shown, a meter bridge is in its balanced state.  The meter bridge wire has a resistance 0.1 ohm/cm.  The value of unknown resistance X and the current drawn from the battery of negligible resistance is             [AMU (Engg.) 2000]

A)         6 W, 5 amp

B)         10 W, 0.1 amp

C)         4 W, 1.0 amp

D)         12 W, 0.5 amp

Correct Answer: C

Solution :

                                         Resistance of the part AC \[{{R}_{AC}}=0.1\times 40=4\Omega \] and \[{{R}_{CB}}=0.1\times 60=6\Omega \] In balanced condition \[\frac{X}{6}=\frac{4}{6}\Rightarrow X=4\Omega \] Equivalent resistance \[{{R}_{eq}}=5\Omega \] so current drawn from battery \[i=\frac{5}{5}=1A\].