Feedback ammeters with high value sensing resistors in the feedback loop have lower Johnson current noise and thus greater sensitivity than shunt ammeters with lower resistance shunts.

• 反馈安培计反馈回路中的取样电阻阻值高，其约翰逊电流噪声就比较低，从而比分流电阻值低的安培计的灵敏度更高。