Question

The reading of ammeter in the adjoining diagram will be

• A. $\frac{2}{17}A$
• B. $\frac{3}{11}A$
• C. $\frac{1}{13}A$
• D. $\frac{4}{15}A$

Answer 1

The correct option is C $\frac{1}{13}A$

Let the current in BAD part is $i$, the current in DB is $i_1$ and the current in DCB is $i_2$.

Apply Kirchhoff’s law at point D, we get

$i=i_1+i_2$ (1)

Apply Kirchhoff’s second law to mesh ABDA, we get

$2i+i+2i_1=2-1$

$3i+2i_1=1$

$3\left(i_1+i_2\right)+2i_1=1$

$3i_2+5i_1=1$ (2)

Apply Kirchhoff’s second law to mesh DCBD, we get

$3i_2+i_2-2i_1=3-1$

$4i_2-2i_1=2$ (3)

By solving the equations (2) and (3), we get

$i_1=\frac{1}{13}A$

Thus, the reading of ammeter is $\frac{1}{13}A$.