An ammeter and a voltmeter are initially connected in series to a battery of zero internal resistance. When switch S1 is closed the reading of the voltmeter becomes half of the initial, whereas the reading of the ammeter becomes double. If now switch S2 is also closed, then the reading of the ammeter becomes:

Explanation

Initially, the ammeter and voltmeter are in series with the battery, measuring the total voltage and current. When switch S1 is closed, the voltmeter's reading halves because the voltmeter now measures across a component with half the total resistance, while the ammeter's reading doubles due to the decreased resistance in series. When switch S2 is closed, the circuit configuration changes further, creating a parallel path that further decreases the total resistance. This results in an increased current, making the ammeter read 3/2 times the value after closing S1. The other options fail to account correctly for these changes in circuit configuration and their effects on current and voltage.