D 2.47 Figure P2.47 shows a circuit for an analog voltmeter of very high input resistance that uses an inexpensive moving-coil meter. The voltmeter measures the voltage V applied between the op amp’s positive-input terminal and ground. The moving-coil meter deflects a small mechanical arm in response to a current. Assuming it produces full-scale deflection when the current passing through it is 100 µA, find the value of R such that a full-scale reading is obtained when V is +10 V. Does the value of the meter resistance affect the voltmeter calibration?
D 2.47 Figure P2.47 shows a circuit for an analog voltmeter of very high input resistance that uses an inexpensive moving-coil meter. The voltmeter measures the voltage V applied between the op amp’s positive-input terminal and ground. The moving-coil meter deflects a small mechanical arm in response to a current. Assuming it produces full-scale deflection when the current passing through it is 100 µA, find the value of R such that a full-scale reading is obtained when V is +10 V. Does the value of the meter resistance affect the voltmeter calibration?
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