✔ 最佳答案
37. A voltmeter measures the potnetial difference (p.d.) across two points in a circuit. In so doing, it is envisaged that it should have a high internal resistance such that it will not draw any current (or as small current as possible) from the circuit. Otherwise the original condition of the circuit would be altered and the voltage measurement would not be accurate.
A typical galvanometer has a very low resistance. Thus, it is essential to connect a high resistance in series with the galvanometer to achieve the purpose as explained above.
In option B: the "voltmeter" would divert a substantial amount of current flowing through it from the circuit, thus altering much the original circuit condition.
In options C abd D: it is clear that most of the current from the circuit would flow through the galvanometer direct (because of its low resistance), instead of flowing through the component to which its p.d. is to be measured.
34. It is just a mis-print in the circuit connected to the secondary coil.