Final answer:
It is not strictly true that only an analog meter should be used for measuring continuously changing current; digital meters can also provide precise measurements and affect the circuit less.
Step-by-step explanation:
When the current level is continuously changing in a circuit, it is not necessarily true that only an analog meter should be used. Both analog and digital meters have their own advantages. Analog meters display readings with a needle moving over a scale, which can make it easier to notice trends or fluctuations in the current. However, digital meters have a high input impedance which means they affect the circuit to a lesser extent, thus providing more accurate measurements. Also, digital meters can detect smaller currents than analog meters since they require less current to operate.
Therefore, for a constantly changing current, if the goal is to observe a trend, an analog meter could be preferred. But for higher accuracy, a digital meter is usually more suitable since it can provide precise measurements without significantly altering the state of the circuit.