Question

In the diagram shown below, the cell and the ammeter both have negligible resistance. The resistor are identical.

Answer 1

Let V be the voltage of the cell and R is the resistance of each resistor. When switch K is not closed then 

\[\frac{V}{\frac{R}{2}} = 0 . 6 . . . . . (1) [\text{ Using V = I }R]\]
\[\text{ Let A be the current, when switch (K) is closed } \]
\[\frac{V}{\frac{R}{3}} = A . . . . . (2)\]
\[\text{ Dividing equation (2) by (1), we get }\]
\[\frac{A}{0 . 6} = 1 . 5\]
\[ A = 1 . 5 \times 0 . 6 = 0 . 9 A\]