Question

If in the circuit in figure, internal resistance of the battery is $1.5\Omega$ and $V_P$ and $V_Q$ are potential at P and Q respectively. What is the potential difference between the points P and Q?

• A. zero
• B. $4volt(V_Q>V_p)$
  
• C. $4volt(V_P>V_Q)$
  
• D. $2.5volt(V_Q>V_p)$

Answer 1

The correct option is D $2.5volt(V_Q>V_p)$

Effective resistance of circuit
$=\frac{5\times 5}{5+5}+1.5=4\Omega$
Total current in circuit, $I=\frac{20}{4}=5A$
Current in arm APB or AQB $=\frac{5}{2}=2.5A$
$V_A-V_P=3\times 2.5=7.5volt{V}_A-V_Q=2\times 2.5=5.0volt\therefore V_P-V_Q=5.0-7.5=-2.5volt$