有些(基本)電阻的PHY!!!!急 謝謝大家!!!!!

Since you did not give a complete description of the question, I suppose you are asked to measure the resistance of the bulb by taking the reading of the voltmeter and ammeter and then calculate the bulb resistance using Ohm's Law.

In that case, there are two points of mistake in your circuit diagram:
(i) the voltmeter should be connected across the bulb so as to measure the voltage across the bulb only. In your drawing, the voltmeter measures the voltage across both the bulb and the sliding resistor.

(ii) One terminal of the bulb should be connected to the "slider" of the sliding resistor and not to the "end" of the resistor. In such connection, the resistance of the circuit, hence the voltage across and current through the bulb, can be varied by adjusting the position of the "slider".