Circuit diagram has a battery of $9 \mathrm{V}$. Calculate the current flowing in the resistors of $12\mathrm{\Omega }$.

  

Figure shows a cell and an ammeter of negligible resistance. All the resistors are similar. The ammeter shows a current of $0.5 \mathrm{A}$ when switch $K$ is open. What will be the reading when switch $K$ is closed ?

Figure shows a cell and an ammeter of negligible resistance. All the resistors are similar. The ammeter shows a current of $0.9 \mathrm{A}$ when switch $K$ is closed. What will be the reading of an ammeter when switch $K$ is open ?