question_answer

If the power dissipated in the \[9\Omega \] resistor in the circuit shown is 36W, then the potential difference across the \[2\Omega \] resistor is:

A) 8V                               

B) 10V    

C) 2V                               

D) 4V

Correct Answer: B

Solution :

[b] \[{{P}_{(9\Omega )}}=\frac{{{V}^{2}}}{R}=36\] \[{{V}^{2}}=36R\] \[V=\sqrt{36\times 9}\] \[V=18V\] This voltage is same across \[9\Omega \] and\[6\Omega \]. [Parallel combination] \[{{I}_{9\Omega }}=\frac{18}{9}=2A{{I}_{6\Omega }}=\frac{18}{6}=3A\] \[{{V}_{2\Omega }}=IR\] \[=5(2)=10V\]