Half Wave Rectifier Type Instrument

Q. The sensitivity of PMMC instrument is $10k\Omega /V$. If this instrument is used in rectifier type voltmeter with half wave rectification the sensitivity will become _______ $k\Omega /V$

1. 4.5

Q. A symmetrical square-wire voltage is applied to an average reading diode voltmeter having a scale calibrated in terms of rms value of a sine wave, the error in meter indication will be

1. 1.11 %
2. 11.1 %
3. 21.1 %
4. 0.45 %

Q. A half wave rectifier type AC voltmeter consists of a series resistance ${}^{\prime }{R}_{ext}^{\prime }$, ideal diode 'D' and PMMC instrument as shown in figure. The internal resistance of PMMC meter is $120\Omega$ and full scale deflection is produced by a DC current of 1 mA. The value of ${}^{\prime }{R}_{ext}^{\prime }$ required to obtain full scale deflection with an AC voltage of 10 V (rms), applied to the input terminal is_______$\Omega$.

1. 4380