Question

The potential difference across $AB$ is $5V$. The voltage of ideal battery is

• A. $40V$
• B. $15V$
• C. $30V$
• D. $10V$

Answer 1

The correct option is B $15V$

Given,

Potential difference across $AB$ is $5V$ Then current through $AB$terminal will be

$I_{AB}=\frac{5}{2}A$

Here 4 ohm and 2 ohm are in series then potential difference of 3 ohm is

$V_3=\frac{5}{2}\times 4+\frac{5}{2}\times 2=10+5=15V$

$I_3=\frac{15}{3}=5A$

Now total current of circuit is,

$I=5+2.5=7.5A$

Voltage of battery is

$V=IR$

$V=7.5\times 2=15V$