Question

The magnitude of i in ampere unit is

• A. 0.1
• B. 0.3
• C. 0.6
• D. None of these

Answer 1

The correct option is A 0.1

Applying Kirchoff's law in following figure.
At junction A:
$i+i_1+i_2=1....\left(i\right)$
For loop (i)
$-60i+(15+5)i_1=0$
$\Rightarrow i_1=3i....\left(ii\right)$
For loop (2)
$-(15+5)i_1+10i_2=0$
$\Rightarrow i_2=i_1=\left(3i\right)$
On solving equation (i),(ii) and (iii) we get $i=0.1A$
Short Trick: Branch current = main current $\left(\frac{Resistanceofoppositebranch}{Totalresistance}\right)$


$\Rightarrow i=1\times \left[\frac{\frac{20}{3}}{\frac{20}{3}+60}\right]$
=0.1 A