F.2 Science Electric current

The ammeter reading increases.
The bulb becomes brighter.

When the switch is open, a current flows through the ammeter, the bulb and the resistor.
When the switch is closed, there is a short circuit (短路) across the resistor. The current would flow through the switch (resistance ≈ 0), but would not flow through the resistor. Since the current does not flow through the resistor, the total resistance of the circuit decreases. This would lead to the increase in current.