Question

Two cells each of e.m.f. 2V and internal resistance 1 ohm are connected as shown. The P.D. between X and Y is

• A. 4V
• B. 2V
• C. 1V
• D. zero

Answer 1

The correct option is B 2V

$\frac{1}{r_{eff}}=\frac{1}{r_1}+\frac{1}{r_2}$
$=\frac{1}{1}+\frac{1}{1}=2$
$\Rightarrow r_{eff}=\frac{1}{2}\Omega$
$\frac{E_{eff}}{r_{eff}}=\frac{E_1}{r_1}+\frac{E_2}{r_2}$
$\Rightarrow E_{eff}=E=2V$
$\Rightarrow PD=E+ir$
$[\because i=0]$
$PD=E=2V$