Physics

Problem

Two loops share a

5\,\Omega

resistor. The left loop contains a

15\,\text{V}

battery and a

10\,\Omega

resistor. The right loop contains an unknown battery

\mathcal E_{x}

and a

20\,\Omega

resistor. Neglect the resistance of the connecting wires. If the current through the shared

5\,\Omega

resistor is zero, what is the value of

\mathcal E_{x}

? a)

25\,\text{V}

15\,\text{V}

30\,\text{V}

37.5\,\text{V}