In the circuit, the two 1 ohm resistors at the top half are connected in series. So the total resistance is 1 +1 = 2 ohms. The other two resistors of 1.5 ohms and 1 ohm at the bottom half are also connected in series. The 2 combined resistances are connected in parallel.
In a parallel circuit, the voltage across each of the components is the same, and the total current is the sum of the currents through each component.
The voltage across the circuit is 2 V. It is to be noted that the ammeter is connected to the resistances in the top half of the circuit.
According to Ohm's law, the current is calculated from I=V/R = 2 volts/2 ohms = 1 A.
Hence, the reading of ammeter in ampere for the following circuit is 1 A.